When States-Systems Unite:
Spatio-Temporal Boundary and Transition Issues
In the Unification of the Central, Far Eastern and Indic States-Systems:

David Wilkinson
Political Science Department
University of California, Los Angeles
dow@ucla.edu

How do we know when two or more states-systems merge and become one?  This is a fairly straightforward theoretical question, but a very challenging historical and metrological problem for the comparative study of the states-systems of civilizations/world system.   What criteria should we use to decide whether, when and where two civilizations/systems of states/world systems have fused to become one?  What standards exist against which we can set candidate cases of linkage?

TERMINOLOGY AND METHODOLOGY
The sociopolitical species under study sports several useful labels.  Its members are “civilizations,” since they are networks of cities; “states-systems,” since they are networks of states; “politico-military networks,” or “PMNs,” since they constitute webs of political, military and diplomatic connections between cities and states; and “world system,” since they possess definable overall power structures.  This paper will use any of these terms that seem appropriate at the moment of use; it need merely be noted that each member of the species scrutinized is at once a civilization, a states-system, a PMN and a world system.
Different aspects of the species invite different methods of measurement.  One approach views members in their aspect of city-networks, and seeks to locate cities, estimate their sizes, and note the distances between them.  By this approach, if neighboring city networks grow and extend themselves one toward another, via the birth of new cities closer and closer to the neighboring network, to the point that the distances between the frontier cities of each network approximate the distance between a frontier city and its next inward neighbor-city, the two networks may be said to have become one.  A variant of this approach would measure intercity travel-time rather than simple distance.

Another approach, which this paper will take, approaches these entities in their aspect of states-systems, and searches for transactional phenomena.  These would be assessed for (political) type, intensity, duration and magnitude.  As intersystemic transactions approach intrasystemic transactions on these metrics, separate systems would be viewed as merging into one.

PHENOMENOLOGY OF POLITICAL-SYSTEMNESS
What are the relevant types of political transactions? Politics involves power, power-seeking, struggles about power, and the application of power; its phenomena display both cooperation and conflict.  Wars are probably the most-noticed such power-transactions, but by no means the only ones.  Members of a political system display their co-membership via bargaining, fighting, agreeing, conquering, ruling, interfering, obeying…. Groups of members of a system ally, league, compensate, balance and bandwagon.  Such, then, are the phenomena which a metrology of systemness must seek to detect and trace.  

BENCHMARKING SYSTEMNESS
Since we are seeking intersystemic transactions that approach intrasystemic transactions, it is appropriate to compare the practices between systems thought to perhaps merging or merged with those within an established system.  The long Rome-Persia duet can serve as a benchmark for pairwise relations betweens well-entangled states; the Eastern Zhou system can do the same for multistate intrasystemic connections.
The long relationship (66 BC—AD 628) between the Roman Empire and its Byzantine successor of the one hand, and the Parthian Empire and its Sassanid Persian successor on the other displays a variety of indications of genuine political linkage, which can be enumerated. Appendix I summarizes Rome-Persia political interchanges: 21 wars, 1 war alliance, 17 treaties (including one “Eternal Peace” that lasted nine years and one “Fifty Years Peace” that lasted ten), 4 interventions in each other’s civil wars, and 4 clientelistic relationships.  (See Appendix I for details.)
The Roman/Byzantine—Parthian/Persian relationship displays a variety of important political transactions: warmaking and peacemaking, conquest and redress, hierarchy and equality, extortion and exchange, demands and concessions, negotiations and snubs, demarcations and redemarcations.  The long continuity, intensity, importance and reiteration of such transactions is so clear and consistent that that interstate relationship can serve as a paradigm or archetype for estimating the existence and depth of a political relationship between the members of pairs of states over some comparable period, and for locating a time-boundary for the beginning (or indeed the end) of such a political relationship.

If, for instance, two states-systems, each unipolar, hegemonic or unified-imperial were to join, we would expect that a single bipolar system would emerge, and that the formerly separate polar states would noticeably begin to negotiate and (fight/agree) over the same sorts of issues that divided/united Rome and Persia: status, boundaries, obedience, vassals, etc.

The Eastern Zhou era (770 BC-221 BC), both in its Spring and Autumn subperiod (770-476 BC) and its Warring States subperiod (476 BC-221 BC), though nominally an empire under the Zhou dynasty, was in fact a multistate system, with interstate relations and formations accordingly more complex than those of the Roman-Persian bipolar pair.  There are systemwide structures of power that show fluctuation: the Eastern Zhou era was occasionally bipolar, as Rome-Persia normally was; but Eastern Zhou was also tripolar, more often multipolar, and ended in unipolarity and the Qin Empire that created “China.”   

Appendix II summarizes the chief systemic political phenomena of the Eastern Zhou.  The most crucial such phenomena for the polimetrics of systemness are leagues of states, alliance wars (pitting groups of states against other such groups), balancing against rising powers, bandwagoning with rising powers, and broad-based conferencing in which several states or leagues seek, and perhaps find, temporary concord.  

A single multistate system might be expected to emerge from two states-systems if one or both confluent systems had been multipolar or bipolar.  The time of confluence of the systems should then by marked by the development of cross-system alliances, alliance wars, balancing, bandwagoning, and/or conferencing.

APPLICATION: MEASURING EURASIAN POLITICAL GLOBALIZATION

There were c. 1500 BC three states-systems in the Eurasian belt of cities and states that ran from East Asia and South Asia through the “Middle East” and into the Mediterranean periphery.  By AD 1945, there was one states-system in this region, and indeed in the globe, as manifested in World Wars I and II, the conferencing that followed each, and the creation of encompassing multistate organizations (or permanent conferences), notably the League of Nations and the United Nations.   All the formerly separate states-systems, including the three cited, had united.  When and how did the networks of cities and states that emerged in the Eastern Hemisphere join to form a single such network?  This paper is a first step in the quest to discriminate the key times, places and manners in which the three cited system fused into one.
Each member of trio of PMNs selected for inspection carries two labels, each useful in one or another context.  The first trio of labels distinguished the (Sinocentric) Far Eastern or East Asian system, the Indic or South Asian system, and the “Central” system: the last term indicates the system that was created in the Near East c. 1500 BC by the expansion, collision and fusion of the Northeast African (aka “Egyptian”) and Southwest Asian (aka “Mesopotamian”) systems, which duly extended itself westward through the Mediterranean basin and eastward into Iran.
The second trio of labels will be used more frequently in this paper: Eastside, Southside and Westside respectively.  These labels emphasize the geopolitical relationships of the trio.  Those relationships are critical to the task of this paper, and will be addressed next.

THE CENTRAL ASIAN BARRIER AND THE GEOPOLITICS OF SYSTEMNESS
There were severe geopolitical barriers to the projection of power from any of the three systems into any other, and therefore to the unification of their power structures.   Central, Indic and East Asian systems were separated by what we shall term the Central Asian Barrier of tall, cold mountains: Tian Shan, Himalayas, Hindu Kush, Pamirs. 
The Tian Shan obstructs movement between the Tarim Basin on its east, more readily accessible from China, and the Fergana Valley and Bactria on its west, moiré readily accessible from Iran.  The Karakorams and the Himalayas even more effectively restrict movement between the Tibetan Plateau on the north and the Indo-Gangetic plain on the south.  The Hindu Kush rather less effectively raises the cost of movement between the valley of the Oxus (the modern Amu Darya) and the Indo-Ganges region.  Considered in their relations to the Barrier, the Far Eastern system was its Eastside, the Indic system its Southside, and the Central system its Westside.  And because the Barrier was a severe impediment to the unification of the three PMNs, and the crossing or evasion of the Barrier was essential to that unification, this paper will ordinarily speak of the three circum-barrier networks as “sides” to the Barrier.
The metric problem arises with respect to the Barrier because the Barrier was by no means absolute: it was semi-permeable, more passable to proselytizers, pilgrims, and preciosity-traders—and to envoys--than to conquerors and armies. For polimetric purposes, it is particularly important to examine the relations of the trio of PMNs in those moments when the barriers were approached or crossed by diplomats and armies, to note when and how and to what degree and for how long what sorts of inter-network connections were established, how and when they were broken—or not. 

THE NORTHSIDE PROBLEM
North of the Barrier lies a belt of desert-punctuated steppes hospitable to nomadism.  Nomadic and semi-nomadic confederations frequently arose to trade, raid, extort, submit, invade, subjugate, settle, or divide.  They will frequently figure in the study of intersystem connections, but are too unstable and unsettled to be characterized as a fourth “civilization,” though they did create capital cities, real and legendary.  Sometimes they obstruct the creation of political linkages (the Scythians and Alexander), frequently they function as members of the eastside system (Xiongnu, Xianbei, Rouran, Göktürks, Uyghurs), sometimes entire peoples moved through one system into another (Scyths and “Hunas” into the southside), and once, notably, a nomadic confederation created a strong intersystemic linkage—the Mongol Empire.

PRINCIPLES OF CASE SELECTION
The power structures of the trio of states systems can be assessed for long periods: the Central system since 1500 BC, the Far Eastern since c. 1050, the Indic since c. 550 BC. This gives c. 2500 pair-years for the Central-Indic relationship and the same for the Far Eastern-Indic relationship, and c. 3000 pair-years for the Central-Far Eastern relationship.  ~8000 pair-years must be pared down, at least for initial examination.
The (rebuttable) presumption here employed for the paring down is that power is easiest to project outside the existing boundaries of a states-system when that system is in a moment of unipolarity, hegemony, or imperial unity and the expansive power is the hyperpower, hegemon or metropole of the system; less easy to project from a polar state in a bipolar moment, still less in a tripolar moment, extremely difficult in a multipolar moment; and either impracticable or inconsequential for a ministate to manage during a nonpolar period. 
Behind this presumption lies another: states have limited attention spans and tend to be preoccupied with mere survival, which is more challenged the weaker they are in their own states systems. The stronger a state is in its system, the more likely it is to engage in ambitious questing.
Technological developments of seapower and, much later, of overland logistics, in the era of the global expansion of modern Central system undermined these presumptions.  For the premodern era, they will be retained, simply as principles of case selection.  We shall look first at the moments of greatest political unity in each of the trio of systems, and ask about the extra-systemic power projection of the strongest states of each.

One way to judge the degree to which, and time by which, the three circum-Barrier networks coalesced into a genuine political system is to examine the politico-military-diplomatic transactions that arose when the control of any Great Power in any of the three networks approached and probed the Barrier.

THE CHIEF POWERS OF EACH SYSTEM
For the Central system, i.e. the westside, the chief superpowers would be Achaemenid Persia, Alexander’s Macedon, Rome vs. Parthia, Rome/Byzantium vs, Sassanid Persia, and the Arab caliphate at about the time of late Ummayads and early Abbasids.  The early Seleucid state can be seen as part of a bipolar or tripolar westside. After the fracturing of the Caliphate, multipolarity became the westside norm.
For the Far Eastern system, the well-known relevant powers would be Qin, Sui/Tang, , Mongol/Yuan, Ming, Manchu/Qing. We would add Tibet and the Uyghur Khaganate. Probably under the Qing, and certainly within a decade after their overthrow, the Far Eastern system was incorporated into the Central network.
For the Indic system, Nanda, Maurya, Gupta, Harsha, Mughals and Marathas are the powers of concern.  The British Raj probably, and the World Wars certainly, constitute the incorporation of the Indic into the Central network.

THE CASES
The following cases represent approaches to the barrier from one side or another or passages through it to another side:
Cyrus the Great and Zhou Dynasty East Asia
Darius and India
Alexander and Zhou Dynasty East Asia
Alexander and India
Seleucus I Nicator and Zhou Dynasty East Asia
Seleucus I Nicator and Chandragupta Maurya
Ashoka Maurya and the Diadochi
Qin and Antiochus III 
Antiochus III and India
Han Wudi, the “Western Kingdoms,” and Parthia
Parthia and India
Augustus, China and India
The Latter Han and Parthia
The Latter Han and Rome
The Sassanids and the Eastside
The Sassanids and the Southside
Eastside-southside connections, 4th to 7th centuries
The Göktürk Khaganates
The Abbasids and the eastside.
The Mongols and the West
The Mongols and India
The Ming and the West
Safavids, Ottomans, Uzbeks and Mughals
Mughals, Marathas, Ming, and Qing. 

There were also entities that for a period bridged, or seemed perhaps to have bridged, the Barrier:

BMAC (Bactria-Margiana Archaeological Complex or Oxus Civilization) 
Chariot peoples
Indo-Greek Kingdoms 
Indo-Scythians 
“Indo-Parthians ” 
“Kushans”
“Indo-Sassanids” 
“Hephthalites” 
Saffarids 
Ghaznavids 
Ghurids 
Timurids

The cases are briefly reviewed in Appendix III, the “bridge” entities in Appendix IV.  To sum up: the Westsiders Cyrus, Alexander and Seleucus I stopped pushing eastward, blocked by terrain and/or northside Scythians.  Alexander, Seleucus I and Antiochus III made brief incursions into northwest India but established no lasting political linkage. Ashoka Maurya sought to recruit the Diadochi to his service, or that of Dharma, without success except in his own inscriptions. Qin Shihuangdi and Antiochus III were separated by intervening powers. Both Han Wudi and the Latter Han found westward projection of power too costly and came to prefer trade with the westside.  Rome and China exchanged inconsequential “embassies” with more than a century’s lag. Parthia and India were separated by successive transitory “bridge” kingdoms (see Appendix IV); the same is likely true of Sassanid Persia and India, despite claims to the contrary. Sassanid Persia sent a fair number of “embassies” to China, without significant political consequences. A potential northside bridge between east and west was broken when the northsiders, Göktürks, themselves divided between east and west, and respectively attached themselves to the eastside and Westside states systems.  A genuine collision between Tang China and the Abbasid caliphate failed to produce a durable linkage.  Saffarids, 
Ghaznavids, Ghurids and Timurids established one or two-man bridges between Westside and southside that somewhat outreached and outlasted Alexander’s.
More impressive, because historically and geopolitically more challenging, was the brief eastside-westside linkage through war and diplomacy established by the Mongol Empire 1235-c. 1301.  Far weaker links were created between eastside and southside by the Mongols.  Mughals, Marathas, Ming and Qing made little eastside-southside headway.   On the contrary, Mughal connections reached behind their Westside Safavid Persian rivals, though the Mughal-Ottoman and Mughal-Uzbek connections seem fairly tenuous.
We end before addressing the durable Westside-southside connection established by West Europeans, especially British, in India, and by Europeans, especially British and Russians, and by Americans and Japanese, in the Far Eastern system.  Like the Rome-Persia connection and the Eastern Zhou, these durable and effective linkages can serve for comparative measurement of their less successful, if often eager, predecessors. 

APPENDIX I.  ROME-PERSIA 66 BC—AD 628

1. War Oppositions
Rome (Crassus) vs. Parthia (Orodes II) over Mesopotamia, Armenia and Syria: 53-51 BC
Rome (Antony, Ventidius) vs. Parthia (Orodes II) over Syria, Judea, and Anatolia: 40-38 BC
Rome (Nero, G. Domitius Corbulo) vs. Parthia (Vologases I) over Armenia: AD 61-63
Rome (Trajan) vs. Parthia (Osroes I) over Armenia and Mesopotamia: AD 113-117
Rome (co-Emperor Lucius Verus) and Parthia (Vologases IV) over Armenia and Mesopotamia: AD 161-166
Rome (Septimius Severus) vs. Parthia (Vologases V) over Mesopotamia: AD 197-198
Rome (Caracalla, Macrinus) vs. Parthia (Artabanus V): AD 216-217
Rome (Severus Alexander) vs. Persia (Ardashir I) over Mesopotamia: AD 230-233
Rome (Maximinus Thrax), The Six Emperors of AD 238, Gordian III, Philip the Arab) vs. Persia (Ardashir I, Shapur I) over Mesopotamia and Armenia: AD 237-244
Rome (Valerian, Gallienus) and Palmyra (Odaenathus) vs. Persia (Shapur I) over Mesopotamia: AD 250-263
Rome (Carus) vs. Persia (Bahram II) over Mesopotamia: AD 282
Rome (Diocletian, Galerius) vs. Persia (Narseh) over Mesopotamia, Armenia, and Caucasian Iberia: AD 295-299
Rome (Constantius II) vs. Persia (Shapur II the Great) over Mesopotamia: AD 337-350
Rome (Constantius II, Julian, Jovian) vs. Persia (Shapur II) over Mesopotamia and Armenia: AD 358-363
Byzantium (Theodosius II) vs. Persia (Bahram V) over persecution of Christians: AD 421-422
Byzantium (Theodosius II) vs. Persia (Yazdegerd II) over Mesopotamia: AD 440
Anastasian War: Byzantium (Anastasius I) vs. Persia (Kavadh I) over subsidy to Persia: AD 502-506
Iberian War: Byzantium (Justin I, Justinian I) vs. Persia (Kavadh I) over Mesopotamia, the Transcaucasus, and Persian demands for subsidy: AD 526-532
Lazic War: Byzantium (Justinian I) vs. Persia (Chosroes I) over Lazica: AD 541-562
Byzantium (Justin II, Tiberius II, Maurice) vs. Persia (Chosroes I, Hormizd IV, Chosroes II) over Armenia, Mesopotamia, and the subsidy to Persia: AD 572-591
Byzantium (Phocas, Heraclius) vs. Persia (Chosroes II) over Asia Minor, Syria, Judea, Egypt, Mesopotamia and the Caucasus: AD 602-628

2. War Alliances
Rome (Pompey) and Parthia (Phraates III) vs. Armenia (Tigranes the Great): 66-65 BC

3. Treaties
Rome (Augustus) and Parthia (Phraates IV) over Armenia and the standards of Carrhae: 32 BC
Rome (Gaius Caesar) and Parthia (Phraates V) over Armenia: AD 1
Rome (Germanicus) and Parthia (Artabanus III) over Armenia: AD 18
Rome (Lucius Vitellius) and Parthia (Artabanus III): AD 37
Rome (Nero, G. Domitius Corbulo) and Parthia (Vologases I) over Armenia: AD 63
Rome (Septimius Severus) and Parthia (Vologases V) over Mesopotamia: AD 202
Rome (Macrinus) and Parthia (Artabanus V) over Mesopotamia: AD 217
Rome (Philip the Arab) and Persia (Shapur I) over Mesopotamia and Armenia: AD 244
First Peace of Nisibis: Rome (Galerius) and Persia (Narseh) over Mesopotamia, Armenia, and Caucasian Iberia (Georgia): AD 295-299
Second Peace of Nisibis: Rome (Jovian) and Persia (Shapur II) over Mesopotamia, Armenia and Caucasian Georgia: AD 358-363
Byzantium (Theodosius II) and Persia (Bahram V) over freedom of religion: AD 422
Byzantium (Theodosius II) and Persia (Yazdegerd II) over Mesopotamia: AD 440
Byzantium (Anastasius I) and Persia (Kavadh I): AD 506
“Eternal Peace”: Byzantium (Justinian I) and Persia (Kavadh I, Chosroes I) over returns of forts and a subsidy to Persia: AD 532
“Fifty Years Peace” of Dara: Byzantium (Justinian I) and Persia (Chosroes I) over Lazica and a subsidy to Persia: AD 562
Byzantium (Maurice) and Persia (Chosroes II) over Armenia, Mesopotamia, and the subsidy to Persia: AD 591
Byzantium (Heraclius) and Persia (Kavadh II, Shahrbaraz) over Asia Minor, Syria, Judea, Egypt, Mesopotamia, the Caucasus, war trophies and a war indemnity from Persia: AD 628-629

4. Interventions in Civil Wars
Parthia (Pacorus I) in Liberators’ civil war in Rome (Liberatores--Brutus, Cassius--vs. Second Triumvirs--Antony, Octavian): 42 BC
Rome (Tiberius, Lucius Vitellius) in Parthian civil war (Tiridates III vs. Artabanus III): c. AD 36
Byzantium (Maurice) in Persian civil war (Chosroes II vs. Bahram VI): AD 591
Byzantium (Heraclius) in Persian civil war (Shahrbaraz vs. Ardashir III): AD 591

5. Protectorates and Vassalships
Parthia (Phraates IV) sends royal-family hostages to Rome (Augustus): 32 BC
Rome (Augustus) installs a client (Vonones I) to rule Parthia: AD 8-12
Rome (Trajan) installs a client (Parthamaspates) as king of Parthia: AD 116-117
Byzantium (Maurice) installs a client (Chosroes II) as Persian emperor: AD 591

APPENDIX II.  Eastern Zhou 770 BC-221 BC.

1. Far Eastern Power Structures during Eastern Zhou

“Snapshots” of power structures in the Far Eastern system have been taken at 25-year intervals from 750 BC to 225 BC during the Eastern Zhou.  These power-structure “moments” begin with nonpolarity and end with the hegemony of Qin; between, there are two unipolar moments, four tripolar moments, four bipolar moments and eight moments of multipolarity. In the bipolar moments of 675 and 650 BC the superpowers were Chu and Qi; in those of 575 and 550 BC the superpowers were Chu and Jin.  In the tripolar moments of 450 and 425, and again in those of 325 and 300 the superpowers were Qin, Qi and Chu. .In the unipolar moments of 275 and 250 Qin was the hyperpower.   (Wilkinson, 1999)

2.  The Number of States in the Eastern Zhou System 

Over the period 722 BC-221 BC, a collection of perhaps 170 states in the system (Walker, 20) shrank and shrank until toward the end, seven survivors were step by step reduced to one (Qin).  The shrinkage was caused by conquests and annexations, carried on increasingly by superpowers and hyperpowers: Chu, Qi and Jin each absorbed more states than did middling powers like Lu, Sung, (old) Wei, Wu or Yen (Walker, 27); Qin conquered Chu, Qi, and the three states into which Jin broke at the endyear of Spring and Autumn.

3. Protectorates, Leagues, Polarization and Alliance Wars

A waystation on the road to annexation was the protectorate, whereby one great power defended one or several smaller powers from the threat of absorption by some other great power.  There grew up around Qi, Jin, Chu and Qin “leagues” of states, which at various times recognized a great-power ruler as a “hegemon” or commander-in-chief of a multistate military force. Over time, there developed a polarization between northern and southern groups of states, the northern states first tending to be led by Qi and then by Jin, the southern states by Chu

Thus Duke Huan of Qi (hegemon 667-643 BC) led four to eight states, intervened in their internal power struggles, drove off invaders, and blocked the northward expansion of Chu.  Duke Wen of Jin (hegemon 636-628 BC) organized an alliance that again blocked the expansion of Chu. 

4. Bandwagoning and Balancing

The practices of balancing and bandwagoning are specific to multistate systems.
Between 678 BC and 546 BC, the state of Zheng, in a central position between the northern and southern states, shifted its allegiances fourteen times, generally realigning with a rising power (Walker, 50-52); Zheng habitually bandwagoned.   

On the other hand, while the state of Qin eventually became supreme power and sole survivor of the states of the Eastern Zhou era, before its final rise its diplomilitary activities focused upon preventing either Jin or Chu and their leagues from gaining full ascendancy (Walker 52); Qin habitually balanced

5. Conferencing

Permanent legations were nonexistent in the Eastern Zhou era, but diplomatic missions between Eastern Zhou states were frequent.  The Dukes of Lu and their officers were frequent travelers to meet rulers of other states halfway, or to visit them in their capitals. Diplomatic notes with proposals were sent; intelligence was exchanged; military instruction was offered. Missions led to bilateral treaties and to alliance meetings for war planning in defense and attack. (Walker, 15-16, 79-85).  

In 579 BC, Hua Yuan of Sung appears to have brokered a peace treaty and alliance between the bipolar superpowers and rival alliance-hegemons Jin and Chu. Going farther, in 546 BC, Xiang Shu of Sung persuaded 14 large states to attend a peace conference with the objective of peace, disarmament and a league of all states.  There did emerge a document decrying war, and there was in fact a noticeable diminution in warfare for about 34 years (Choyun Hsu 56-57; Keishiro Iriye, Recueil des Cours 1967, 52-53).

6. Power Projection into Multistate Systems

Let us assume the existence of an ongoing multistate system such as that of eastern Zhou, with annexations, protectorates, leagues, polarizations, alliance wars, bandwagoners, balancers, intensive diplomacy, conferencing, and perhaps utopian dreaming.  Given then a state at one time external to the multistate system that seeks to project its power and inject itself into the system, we must look for evidence that it has in fact been brought into the above characteristic institutions and practices of multistate systems.

Two states that in fact provide just such evidence of self-injection into the eastern Zhou system are Wu and Yue.  Wu lay to the east of the system, was brought into it by Jin as an ally against Chu, and became a great power in the system; Yue lay to the south of Wu and was brought into the system as an ally of Chu against Wu, destroyed Wu, and briefly replaced it as a great power.  Both Wu and Yue were brought into the preexisting hostile polarized alliance structures of the Eastern Zhou system.

So when inquiring when and whether an outside state has entered a multistate system, it is to its concrete participation in the alliance structures, the war system, the bandwagoning and balancing and conferencing of the system that we should look for a determination. 

APPENDIX III: CRITICAL CASES AND CONNECTIONS

Cyrus and Zhou Dynasty China

Whether Cyrus the Great of Persia (r. -530 BC) was killed in battle (Herodotus 1.214, Berossus Bursten ed. p. 28), mortally wounded (Ctesias, Llewllyn-Jones ed. p. 173), taken prisoner and crucified (Diodorus 2.44) or died after peacefully philosophizing (Xen. Cyro. 8.7) , there is no evidence in the westside histories that he opened a lasting political connection beyond the Jaxartes, let alone to the Yellow River states.  Instead he founded a city, which the Greeks called “Cyro-polis”; Strabo (11.11.4) calls it simply “Cyra,” and terms it the last of the places founded by Cyrus and the boundary of the Persian Empire.  

On the Eastside, the Yellow River states c. 530 BC were in their late Spring and Autumn period and formed a multi-state system with four great powers, Qi in the northeast, Qin in the northwest, Jin in the north-center, Wu in the east, and Chu in the south, and numerous smaller powers.  This system was in a condition of intense interstate imperialism, hegemonism, diplomacy and warfare, especially as between leagues centered on Jin and Chu. (Walker, 15, 55, 87-91 et passim.)  There is no sign in the ancient records that the eastside power-structure had extended or felt any projections of political power across the westerly Barrier.

Cyropolis may accordingly be treated as the northeastward limit reached by the Westside system.

Alexander and Zhou Dynasty China

Alexander conquered Bactria and Sogdia and confronted the Asian Scythians  at the Jaxartes, with mixed results (Arrian 3.29-4.22). Despite military victories, the Macedonians did not invade the desert, considering pursuit impracticable; Alexander contented himself with having “subdued the Scythians as far as the desert” (Arrian  5.25).  Having conquered Cyropolis, in 329 BC Alexander replaced it with “Alexandria the Furthest,” “Alexandria Eschate” (Arrian 4.1, 4; Curtius 7.6.25), modern Khojand, Tajikistan), and turned his invasions toward India.  Alexander’s later speech (325 BC) to his mutinous army in the Indus Valley (Arrian 5.26) contains a geography of Asia that recognizes Scythia and India, but not China.

The eastside system at the time of Alexander’s peak eastern conquests was in the Warring States period, with most small powers absorbed by a few larger states.  Qin in particular was on the rise, and the other six major powers (Yan, Zhao, Han, Wei, Qi and Chu) are said to have formed a “vertical alliance” to constrain it.  Again there is no sign that political power was crossing the Westside-eastside barrier.

Darius and India

Darius (r. 522-486 BC) invaded India and conquered its small peripheral states of the Indus Valley c. 518-515 BC.  (Herodotus 4.44) Darius then departed westward to put down a Babylonian revolt, drive off an attack by European Scythians, and fail to conquer Greece.  He left behind two Indus “satrapies” (governorships), with an enormous population, from which he exacted a tribute larger than that of any other part of the empire (Herodotus 3.94).
 
Post-Darius, the picture of Achaemenid Central-Indic relations becomes unclear. Darius’ successor Xerxes I (r. 486-465 BC) was preoccupied with western war in Greece; Artaxerxes I (r. 465-424 BC) concentrated on intrigues in Greece and a revolt in Egypt; Darius II (r. 423-404 BC) was focused on Greece, Artaxerxes II (r. 404-358 BC) and Artaxerxes III (r. 358-338 BC) on Greece, Egypt and civil war; Darius III (r. 336-330 BC) lost the empire to the Macedonians.

Persian India provided Xerxes (r. 486-465 BC) with infantry archers, cavalry archers and chariot archers (Herodotus 7.65, 86), but nothing in terms of Indic-system political intelligence or political connection to the more important states of the Gangetic plain; for Herodotus 4.40, Macaulay trans.) says “Asia is inhabited as far as the Indian land [i.e. the Indus Valley]; but from this onwards towards the East it becomes desert, nor can any one say what manner of land it i.”  Also: “That part of the Indian land which is towards the rising sun is sand; for of all the peoples in Asia of which we know or about which any certain report is given, the Indians dwell furthest away towards the East and the sunrising; seeing that the country to the East of the Indians is desert on account of the sand.” (Herodotus 3.98, Godley trans.)  So Greek knowledge of what we call ancient “India,” acquired via Persian intermediacy, stopped then at the Thar desert, a detached part of the Central Asian Barrier..

Darius’ invasion is considered contemporaneous with the floreat of King Bimbisara (variously dated), Haryanka dynasty ruler of Magadha, in the lower Ganges plain.  On the Indic side, no record of Magadha-Persian political intercourse has been found.

Alexander and India

Alexander invaded India in 326 BC. Persians were not among his opponents; the local rulers were Indian kings, notably Taxiles, Porus, and Abisares. (Arrian 4.22-5)  After Alexander had crossed all but one of the “five rivers” of the Punjab, his army, hearing that the lands lying before them was well ruled and very well armed, mutinied and refused to advance further.  “For having had all they could do to repulse an enemy who mustered only twenty thousand infantry and two thousand horse, they violently opposed Alexander when he insisted on crossing the river Ganges also, the width of which, as they learned, was thirty-two furlongs, its depth a hundred fathoms, while its banks on the further side were covered with multitudes of men-at-arms and horsemen and elephants. For they were told that the kings of the Ganderites and Praesii were awaiting them with eighty thousand horsemen, two hundred thousand footmen, eight thousand chariots, and six thousand fighting elephants. And there was no boasting in these reports. For Androcottus, who reigned there not long afterwards, made a present to Seleucus of five hundred elephants, and with an army of six hundred thousand men overran and subdued all India.” (Plutarch, Alexander, 62, trans. Perrin)

Similarly Diodorus: Alexander “questioned [an Indian kinglet] Phegeus about the country beyond the Indus River,45 and learned that there was a desert to traverse for twelve days, and then the river called Ganges, which was thirty-two furlongs in width and the deepest of all the Indian rivers. Beyond this in turn dwelt the peoples of the Tabraesians and the Gandaridae, whose king was Xandrames. He had twenty thousand cavalry, two hundred thousand infantry, two thousand chariots, and four thousand elephants equipped for war.” (Diodorus 17.93, Loeb) Similarly: “the tribe of the Gandaridae… possesses the greatest number of elephants and the largest in size. Consequently no foreign king has ever subdued this country, all alien nations being fearful of both the multitude and the strength of the beasts. In fact even Alexander of Macedon, although he had subdued all Asia, refrained from making war upon the Gandaridae alone of all peoples; for when he had arrived at the Ganges river with his entire army, after his conquest of the rest of the Indians, upon learning that the Gandaridae had four thousand elephants equipped for war he gave up his campaign against them.” (Diodorus, 2.37, Oldfather trans.)

Another account: Alexander “learned that beyond the river there was a journey of twelve days through desert wastes and that then they came to the Ganges, the greatest river of all India, and that on its farther bank dwelt the races called Gangaridae and Prasii; that their king was Aggrammes and that he was blocking the roads with 20,000 cavalry and 200,000 infantry. Besides this, he was leading 2000 chariots, and, a special cause of terror, elephants, of which Phegeus said that he had as many as 3000.” (Curtius, 9.2, Rolfe trans.)

Alexander urged them to the invasion of the Ganges Valley and conquest to the “Eastern Sea”(Arrian 5.25-26).  He was responded to by Coenus, son of Polemiocrates, along the following lines: “…. [T] thyself seest how many Macedonians and Greeks started with thee, and how few of us have been left. Of our number thou didst well in sending back home the Thessalians at once from Bactra, because thou didst perceive that they were no longer eager to undergo labours. Of the other Greeks, some have been settled as colonists in the cities which thou hast founded; where they remain not indeed all of them of their own free will. The Macedonian soldiers and the other Greeks who still continued to share our labours and dangers, have either perished in the battles, become unfit for war on account of their wounds, or been left behind in the different parts of Asia. The majority, however, have perished from disease, so that few are left out of many; and these few are no longer equally vigorous in body, while in spirit they are much more exhausted.” (Arrian, 5.27, trans. Chinnock; cf. Curtius, 9.3.) 

“Alexander observed that his soldiers were exhausted with their constant campaigns. They had spent almost eight years among toils and dangers…. There had been many losses among the soldiers, and no relief from fighting was in sight. The hooves of the horses had been worn thin by steady marching. The arms and armour were wearing out, and Greek clothing was quite gone. They had to clothe themselves in foreign materials, recutting the garments of the Indians. This was the season also, as luck would have it, of the heavy rains. These had been going on for seventy days, to the accompaniment of continuous thunder and lightning.”  (Diodorus, 17. 94, Oldfather trans.) Balked, Alexander turned back, and never resumed his Indian conquests.

Contemporaneous with Alexander’s invasion was Dhana Nanda, the last ruler of the Nanda dynasty of Magadha in the Ganges plain.  Reading “Gangaridae” (people of the Ganges) with Curtius rather than “Gandaridae” (people of Gandhara) with Diodorus, it would have been Magadha which Alexander chose not to encounter.  Two years later, 321 BC, as it chanced, the Nanda dynasty fell; had Alexander moved a bit later, and faced a disordered state, the history of the connections between the Westside and Southside networks might have eventuated quite differently.

Seleucus I Nicator and Zhou Dynasty China 

Alexander left his officers Peithon (as satrap of the Indus) and Eudemus (as troop commander). When Alexander’s empire fell apart after his death in 323 BC, both Peithon and Eudemus returned westward, bringing their Macedonian troops with them and leaving a power vacuum, only to die in the Wars of the Diadochi (“successors”) c. 322-275 BC. One of the several survivors of the Diadochic Wars was the cavalry commander Seleucus I Nicator.  Seleucus acquired the eastern end of Alexander’s empire, including Bactria, Sogdia, and all the adjacent peoples “that had been subdued by Alexander” (Appian, Syrian Wars 9.55), but apparently no more in the easterly direction (unlike his exploits on the southside). Ruling 306-281 BC, Seleucus’ military activity was aimed at India (305-303 BC) and Europe (to 281) rather than the Eastside, of which he, like Alexander, may well have been ignorant.  Antiochus I Soter (r. 281-261 BC) was preoccupied with fighting in Anatolia and Syria; so was Antiochus II Theos, under whom the Bactrian and Parthian satraps revolted (255 and 247-245 BC respectively). Both satrapies were lost, one becoming the Parthian Empire (247-224 BC) and the Greco-Bactrian kingdom, which allied against the Seleucids.  Their Seleucid successors, to 223 BC and the reign of Antiochus III the Great, were preoccupied with revolts and western wars.  

During the peak of Seleucid power under Seleucus I Nicator, the warring States of Eastern Zhou China were fixated upon their struggles with one another, and especially their alliances.  Two “vertical” alliances against Qin (334-300 and 287-286 BC) alternated with two “horizontal” alliances that included Qin (300-287 and 285-284 BC).  Qin, in the best position to expand toward the Westside, instead alternated struggles for survival with expansion eastward within the Warring States network.

Seleucus I and Chandragupta Maurya

Seleucus apparently attempted to surpass Alexander’s achievements in India.  “The whole region from Phrygia to the Indus was subject to Seleucus. He crossed the Indus and waged war with Androcottus, king of the Indians, who dwelt on the banks of that stream, until they came to an understanding with each other and contracted a marriage relationship.” (Appian, Syrian Wars 9.55).  Seleucus cannot have been very successful in this India campaign, for he made peace with Chandragupta (who r. 324-297 BC), allegedly yielding provinces though gaining elephants, and departed for his western wars.  “Seleucus Nicator gave [Parapamisodae, Arachosia and Gedrosia] to Sandrocottus, upon terms of intermarriage and of receiving in exchange five hundred elephants” (Strabo, Geography 15.2.9).  These three areas were Seleucus’ entire Southside frontier; though the reality of the territorial transfer is uncertain.  The elephant-gift seems plausible; Seleucus evidently had elephants at the Diadochic Battle of Ipsus 301 BC, as did his opponents (Plutarch, Demetrius 28; Diodorus, 20.113.4 and 21.Fr. 2).
Central-Indic political connections after the Seleucus-Chandragupta war were scanty. Two Greek “embassies” are recorded: Megasthenes lived with Seleucus, visited Chandragupta, and wrote a treatise on India; Deimachus visited Chandragupta Maurya’s son Bindusara (r. c. 320–273 BC). The work of both “embassies” seems mostly to have consisted of collecting information on India’s geography and resources. 

Ashoka Maurya and the Diadochi (the Successors of Alexander)
Bindusara’s successor Ashoka (r. c. 268 – c. 232 BC) forcibly conquered most of the Indian peninsula. Ashoka sent no armies westward, rather emissaries to propagate Buddhism, including among the Greeks, and proclaimed its conquest of the Hellenistic kingdoms: “Now it is conquest by Dhamma that Beloved-of-the-Gods considers to be the best conquest. And it (conquest by Dhamma) has been won here, on the borders, even six hundred yojanas away, where the Greek king Antiochos rules, beyond there where the four kings named Ptolemy, Antigonos, Magas and Alexander rule….everywhere people are following Beloved-of-the-Gods' instructions in Dhamma.” (Rock Edict 13) The recipients of these instructions were Asoka’s Seleucid neighbor Antiochus II Theos of Syria (r. 261–246 BC), Ptolemy II Philadelphos of Egypt (r. 285–247 BC), Antigonus II Gonatas of Macedonia (r. 277-274 and 272-239 BC), Magas of Cyrenaica (r.274-250 BC), and Alexander II of Epirus (r. 272-242 BC). None of these warrior-kings appears in fact to have followed instructions in Dhamma, and the Rock Edicts, while evidencing Westside-Southside contact, cannot be seen as reflecting a genuine political network-connection.

Qin and Antiochus III

From 230 BC, King Zheng of Qin successively conquered the six surviving eastside states, Han, Zhao, Yan, Wei, Chu, and Qi, rolling up the map in 221 BC.  Zheng promptly proclaimed himself Emperor Shi Huangdi and busied himself with imperial undertakings until his death in 210 BC.  Shi Huangdi was chiefly reoccupied with wars of conquest and colonization to the south (against Yue/Viet).  He undertook a limited expansion against the Xiongnu nomadic confederacy to the north and northwest, in the “Ordos loop” of the Yellow River, but soon adopted a defensive posture on that front, expressed in Great-Wall-building works.  In effect, the Xiongnu confederacy effectively prevented Qin diplomatic or military penetration toward the Westside.

Qin Shi Huangdi’s Westside contemporary was Antiochus III the Great of the Seleucid Empire (r. 222-187 BC), ruling from Antioch, Syria.  Antiochus was a successful eastward conqueror who vassalized Parthia in 209 BC but was held off by Euthydemus I of Greco-Bactria 208-206 BC and thus had no way to invade the Eastside, despite a possible opportunity offered by the 210-206 BC death throes of the Qin dynasty and the 206-202 BC Chu-Han Contention for the rule of the Qin-created Chinese Empire.   In any case, Antiochus became preoccupied with wars on his western front, first against Ptolemaic Egypt and then, to his great cost, against Rome.

Antiochus III and India
Antiochus having come to terms with Euthydemus of Greco-Bactria headed for India 206-205 BC.  “He crossed the Caucasus [sc. Hindu Kush] and descended into India; renewed his friendship with Sophagasenus the king of the Indians; received more elephants, until he had a hundred and fifty altogether; and having once more provisioned his troops, set out again personally with his army: leaving Androsthenes of Cyzicus the duty of taking home the treasure which this king had agreed to hand over to him. Having traversed Arachosia and crossed the river Enymanthus, he came through Drangene to Carmania; and, as it was now winter, he put his men into winter quarters there. This was the extreme limit of the march of Antiochus into the interior….” (Polybius, Histories 11.34)  As noted, Antiochus returned to wage war in the west, where he was successful against Egypt but lost much territory to Rome, whereupon his eastern provinces revolted. The later Seleucids were preoccupied with Rome, rebellions and Parthia, and did not reconnect to India.
The identity of “Sophagasenus” is uncertain and a subject of speculation.  The Maurya Empire declined after Ashoka, and some borderlands broke off.  At the time of Antiochus’ visit, the Maurya ruler was Shalishuka (r. 215-202 BC), of whom little is known.  “Sophagasenus” may have been a Maurya or an independent border kinglet.  Ibn either event, no significant or durable political connection between networks was established, although the form of the transaction, which has the look of a tribute payment, indicates that if it had become routine such a link would have endured as long as the transactions continued.

Han Wudi, the “Western Kingdoms” and Parthia 

In the early years of the Former Han Dynasty (206 B.C.-A.D. 9) Han was tributary to the steppe Xiongnu, who blocked the westward path to any projection of Han political power.  The Chinese emperor Han Wu (r. 141-87 B.C.) broke out of the Han’s tributary vassalage, colonized the Tarim basin, and sent agents to the Westside.   Zhang Qian (active 138-125 BC) seems to have been the first envoy from the Far Eastern network to report upon the Central network. Traveling through the Tarim Basin, he visited urbanized Ferghana, the nomadic Yuezhi of Transoxiana, the petty chiefdoms that were Yuezhi-dominated relics of Greco-Bactria, and the nomads of Sogdiana; he passed on reports of Sind, Parthia and the Seleucids. Zhang Qian sought without success to obtain an alliance with the Yuezhi against the Xiongnu whereby the Yuezhi would have returned to their former lands in Gansu and expelled the Xiongnu with Han assistance. Zhang Qian later worked on Han ties with the Wusun, then a semi-nomadic people of the Ili valley, who served as Han horse suppliers and occasional allies or vassals in the 1st centuries BC and AD.
On the Westside, the nearest comparable power to Han in the days of Wudi was Parthia.  The Iranian state of Parthia under the Arsacid dynasty took the eastern portion of the Westside network away from the Seleucid Empire, and alternated wars with Rome and peace-and-boundary treaties with Rome, struggling or compromising over the domination of Armenia and Mesopotamia. Mithridates I (r. 165-132 BC) raised Parthia from a small state lying north of the Seeleucid Empire, between Greco-Bactria to the east and the Caspian Sea to the west, into a major power in the Central power structure, firstly during his rise by seizing territory from Greco-Bactria, then by taking all the Seleucid holdings from Mesopotamia to the Indus (144-139 BC; Orosius, Against the Pagans 5.4).
Mithridates’ son Phraates II reduced Seleucid holdings to Syria 130-129 BC, but was forced to attend to his northeastern frontier when Xiongnu displaced Tocharians/Yuezhi who in turn displaced Scyths/Sakas; nomadic forces destroyed the Greco-Bactrian state and invaded the Parthian Empire, and Phraates II was defeated and killed while resisting the invasion, as was his successor Artabanus.  (Justin, Epitome 42.1) Thereafter a Yuezhi state was established in Bactria.
Parthia recovered noticeably under Mithridates II (r. 124-90 BC; Justin 42.2). It was during his reign that Zhang Qian reported that Fergana, Bactria and Parthia were “rich in unusual products,” militarily weak, and desirous of Han goods.  This should probably be seen as an intelligence report, which may be rephrased: trade could be opened between Han and the Westside, since each had goods the other desires; but war could also prove profitable, since the Westsiders were weak.  
Whatever Zhang Qian’ intentions, both war and trade in fact ensued.  In 104 to 101 BC, Emperor Han Wudi waged the “War of the Heavenly Horses” upon Dayuan/Fergana to secure horses of high quality. A thousand horses were acquired as tribute and a complaisant ruler was installed; however, the cost was the destruction of half the second army sent, the first having been totally unsuccessful.
Thereafter Han Wudi seems to have become more cautious as regards the military weakness of the western states; at any rate, he dispatched no more armies in that direction, and so lost none. Instead, around 100 BC, envoys from Han visited Parthia, and a reciprocal visit was made by Parthians. Han “embassies” went to the other nations studied by Zhang Qian, with five to ten 100-plus person “embassies” being sent out per year. These “embassies” appear to have been in fact trade missions, or perhaps even merchant caravans taking advantage of the westerners’ desires for Han goods, for while Central-Far Eastern political contacts remained tenuous, commercial contacts and Silk Route trade flourished.
It may be noted that Han Wudi (the “warlike Han emperor”) showed far less politico-military restraint vis-à-vis Han’s nearer neighbors, invading, conquering and annexing several states. To the south Han seized Minyue (now Fujian Province), Nam Viet (now areas in Guangdong and Guangsi provinces and northern Vietnam), and Dian (now part of Yunnan province). In the north, the earlier Han appeasement of the steppe-nomad Xiongnu confederation gave way to repeated campaigns that ultimately drove the Xiongnu north of the Gobi desert. In the northeast, a military campaign was undertaken against Korea, but with no lasting issue.
In sum, a definite and durable economic linkage between Westside and Eastside emerged.  Politically, not so: both alliance (Yuezhi) and conquest were tried, failed and abandoned.

Parthia and India
“Mithridates [i.e. Mithridates I, r. to 132], the sixth king of the Parthians in line from Arsaces…attacked the city of Babylon and invaded all her territories. He next subdued all the tribes that dwelt in the country between the Hydaspes and Indus rivers and extended his bloody rule even to India.” (Orosius, Against the Pagans 5.4)
However long this “bloody rule” might have lasted, the Parthia-India borderlands soon fell into a chaos where invasive regional kingdoms of limited size and duration, Indo-Greeks, Indo-Scythians, Indo-Parthians and Kushans, successively flourished: see Appendix IV. 
Westside-Southside political relations in the Parthian period seem tenuous to nonexistent.  Westside invaders conquered for a while, became naturalized as it were, and were conquered in their turn, but “what goes to India stays in India.” The bubble kingdoms of the borderlands required no attention from Parthia, which was forever under existential threat from imperial Rome.

Augustus, China and India
On the Westside, Parthia after Mithridates II became preoccupied with dynastic struggle and wars with Rome.  Parthia became a client state of Rome during the reign of Augustus Caesar in Rome and Phraates IV (r. 37-2 BC) in Parthia; this may have been the epoch when envoys from China and India reached Rome..
The Roman emperor Augustus (r. 27 BC-AD 14) received envoys from the Seres (likely China) and India, bringing gifts and seeking friendship. The visitors reported that their journeys had taken four years. (Florus, per Yule)  Nothing further is seen on the Westside for more than a century.
Augustus’ power is contemporaneous with the final Emperors of Former Han, Cheng (33-7 BC), Ai (r. 7-1BC) and Ping (r. 1BC-AD 6), and the one-man “Xin dynasty” of Wang Mang (AD 9-23).  Internal troubles and power struggles preoccupied the state during the final years of Former Han.  By the time of Wang Mang, the Xiongnu had reasserted themselves as a power in the Ordos and hegemon in the “Western Regions” of the Tarim, with a military standoff between Xin and Xiongnu.  Between Rome and Xin, the Xiongnu, Yuezhi and Parthians intervened, offering little scope for Roman-Xin diplomacy.
During Augustus’ rule, India was much divided, with Indo-Greeks and Indo-Scythians fading and Indo-Parthians briefly flourishing.  Parthia lay between Rome and the Indic states, and India had nothing to fear from Rome or to offer her politically.  Trade once again is quite another matter. As for Parthia itself, its reach toward the Eastside network was blocked by the northside Scythians.

The Latter Han and Parthia
A “Latter Han” dynasty succeeded Wang Mang’s Xin, ruling China AD 25-220.
The Latter Han Empire got west as far as the Tarim Basin, for which it competed with the Xiongnu confederacy 133 BC-AD 89. Latter Han policy toward the Tarim was one of hegemony (“protectorate”) rather than empire or colonization, and the Latter Han did not often project power west of the Tarim. 
The Latter Han general Ban Chao conquered the Tarim Basin city-statelets AD 74-91 and repelled a Kushan invasion in 90. Ban Chao sent an envoy, Gan Ying, to the west in AD 97; aiming at Rome, Gan Ying only reached Parthia, at the court of Pacorus II. In Parthia he compiled a report, not necessarily any more accurate than that of Megasthenes on India, on Roman customs and products. Pacorus II of Parthia (r. 78-105) sent an embassy to Han, which styled Parthia “Anxi.” After Ban Chao’s retirement in AD 102, Han control of the Tarim lapsed, and the Xiongnu were again rivals.
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The Latter Han and Rome
 Roman “embassy” reached China AD 166, in the reign of the Latter Han Emperor Huan. It came perhaps from Marcus Aurelius, r. AD 161-180, but more likely from his predecessor, Antoninus Pius, r. AD 138-161.  The reign of Antoninus Pius was, for Rome, notably peaceful, as was the early part of the reign of Vologases IVof Parthia (r 147-191); but the Roman-Parthian wars resumed under Marcus Aurelius (war AD 162-166). Envoys would have found it difficult to travel from Rome through Parthian territory during the war years.  The Roman traveler claimed to be sent by “Andun,” which would be Antoninus, the family name of Marcus as well.  The “embassy” was inconsequential.

The Sassanids and the Eastside
The Sassanid Persian Empire (AD 224-651) controlled Iran and neighboring territories between the fall of Parthia and the rise of the Islamic Arab Caliphate, extending at its peak to Egypt, Fergana and the Indus. Like its predecessor Parthia, Sassanian Persia was mainly preoccupied with western-frontier wars with the Roman-Byzantine Empire.
China, from the fall of the Latter Han (AD 220) to the rise of Sui (AD 581), was divided (except for AD 280-304), and largely at war among the successor states, many of them the products of non-Han immigration.  There was evidently little capability or inclination to project power toward the Westside.
Chinese documents do report 13 Sassanian “embassies” to one or another of the divided Chinese states AD 455-555. A Persian embassy is reported as paying “tribute” to the Liang state in south China in 547; however, all Chinese reports of “tribute” must be taken with more than a grain of salt. Perhaps the Persians brought gifts, and received gifts of greater value to them; but most likely it was a trade mission.
Chosroes II (r. 590 and 591-628) ruled Sassanian Persia at its imperial peak; Sui Yang-ti reunited and ruled China (605-617).  Chosroes briefly conquered Egypt and much of Roman Asia, also controlling Sogdia and the edge of India; Yang-ti invaded Champa to the south (at high cost) and (disastrously) the Korean kingdom of Goguryeo to the northeast, but reconstructed the Great Wall to the north, implying a defensive policy at that borderland. Embassies were exchanged by Sui Yang-ti and Chosroes II; but these appear to have involved only deliveries of information
Yazdegerd III, the last Sassanid ruler (r. 632-651) sent an embassy to Tang in 638, presumably to request military help against Gökturks to his east or Arabs to his west; he got none. The Sassanid heir fled to China at the Islamic-Arab conquest.

The Sassanids and the Southside
An inscription of Shapur I (r. 240-270) declares his appointment of a son (and later emperor) Narseh as governor of Sindh.  In his time, “Indo-Sassanian” Persians established themselves as rulers (“Kushanshahs”) over the weakened Kushan Empire Gandhara at the north of the Indus basin. 
An Indic dynasty, the Guptas, acquired control of the Ganges region under Chandragupta I Gupta (r. c. 320-c. 335).   His successors Samudragupta (r.c. 335-c. 375) and Chandragupta II Vikramaditya (r. c. 375 or c. 380-c.415) are supposed to have conquered widely in India, including the northwest. On the other hand, the Sassanid Shapur II (r. 307-379) is said to have re-entered northwestern India. Chandragupta II is credited in Indic sources with conquering the Oxus and across the Himalayas, subjugating the Persians and exterminating the Sakas and Hunas. These boasts should be viewed cautiously, since Sassanid Persia under the contemporaries of Chandragupta II, i.e. Ardashir II (379-383), Shapur III (383-388), Bahram IV (388-399) and Yazdegerd I (399-420), though weaker than under Shapur II, remained preoccupied with its perennial Roman problem, and does not provide evidence of an Indic conquest.  Evidence of the clashes or treaties that would be expected as between such conquerors is lacking. There are various tales, not well substantiated, of alliance and marriage relations between Bahram V (r. 420-438) and India, where Kumaragupta I (r. c. 414-c. 455) ruled the Gupta empire; again, substantiation is wanting.  There is no basis at this time for asserting a political linkage between Sassanid Persia and Gupta India.

Eastside-Southside Connections, 4th to 7th Centuries
The Chinese Buddhist monk Faxian (Fa-Hien, Fa-Hsien; 337-c. 422) visited India (319-414) during Chandragupta II’s reign and collected scriptures and images.  The polities along his route were local, peaceable, and religious.  No signs of political connections between eastside and southside are noted.
The Chinese Buddhist monk Song Yun was dispatched to northwest India 518-522 to collect Buddhist texts by Dowager Empress Hu, then regent of the Northern Wei Dynasty, in control of north China as against the south China dynasty of the Southern Qi.  Song Yun met the Hephthalite “king,” who had control over more than forty kingdoms; the king supposedly prostrated twice and received an Imperial edict from the Northern Wei Dynasty on his knees (Chavannes, 404).  This report no doubt pleased Song Yun’s patroness, but should be viewed with great caution.  No political linkage should be deduced from the purported grovel, and no noticeable politico-military consequences ensued.
The Chinese Buddhist monk Xuanzang eluded a Tang Dynasty prohibition of foreign travel and visited India afoot 629-645 during the rule of Emperor Taizong (r. 626-649).  He met several local kings enroute, as well as the more formidable Khan of the Eastern Göktürks (presumably Illiq Kaghan, r. 620-630, the visit predating the Tang destruction of the Kaghanate in 630).  Xuanzang’s visit also coincided with the Buddhist empire of Harsha (r. 606-647) in North India.  The countries seemed peaceable and prosperous, with many monasteries and many monks.  Tang was preoccupied with wars in the northwest and in Korea, Harsha with war in south India.  
No political eastside-southside political connection was reported nor did one develop, though Tibet, a growing power under Songtsän Gampo (r. 618-650), was a major politico-military problem for Tang Taizong.  However, several missions in both directions between Harsha’s capital Kanauj and Taizong’s capital Chang’an are recorded between 641 and 648.  These seem to have involved gifts, religious texts, and technological transfer rather than politics.  Harsha proved, like Alexander, a one-generation wonder: he raised his hereditary Vardhana kingdom to great-power status; it fell to pieces at his demise.  

The Göktürk Khaganates
The nomadic confederacies of the Xiongnu (fl. 3rd-1st centuries BC), Xianbei (fl. 2nd-3rd centuries AD), and Rouran (fl. 4th-6th centuries AD) had their main fighting, tributary, vassalage, alliance and intermarriage relationships with eastside states.  Göktürks, during their First Khaganate (552-c.580) began by following the same pattern, but their western viceroy Istämi Yabgu (r. 553-576) diplomatic contacts with the Byzantine Empire and cooperated with Sassanid Persia (Chosroes I) in 557 to defeat the Hephthalites.  The potential political bridge thus opened up was closed quickly when the Khaganate fell into civil war and divided into an eastern part linked primarily to Sui and Tang and a western part linked primarily to Byzantium and Persia; both halves were temporarily subjugated by Tang c. 630-659, esp. under Emperor Taizong (r. 626-649). Between 659 and 662, in the rule of Emperor Gaozong (r. 649-683), Tang was able to install puppet kaghans west of the Pamirs, thus at least nominally briefly controlling Fergana, Transoxiana and Herat. 

The Abbasids and the Eastside
In the 7th-9th centuries, it could be argued that a “normal” four-power Eurasian constellation linked eastside, northside and westside, with some southside connections as well. 
The northside saw the succession of a nomadic second Göktürk Khaganate (fl. c. 682-734) and then a semi-nomadic Uyghur Khaganate (fl. 744-840s); the eastside was divided between the Tibetan Empire (fl. c. 635-842), which impinged upon the southside and westside as well, and Tang China (fl. 618-690, 705-755, 817-820, 840-859), which maintained northside links and had Westside connections; the Westside was represented by the successive Arab caliphates of the Ummayads and the Abbasids. 
A “normal” four-power constellation would display pairs of states alternating fighting with peacemaking, trios and quartets of states alternating balancing with bandwagoning, all the while for each member state florescence alternates with decline. 
The main actual transactions in the 6th-8th century quartet, so far as they are recorded, are as follows.  An empire arose in Tibet and flourished c. 608-842. An embassy was sent to Tang China in 634 with demands for a princess bride for the first Tibetan Emperor, Songtsän Gampo (r. 618-650); there was Tibetan-Tang war in 635-636 wars and an interdynastic marriage in 641, another war in 650. Tibetans conquered the Tarim from Tang in 670. 
The Göktürks successfully promoted and then exploited the Khitan Li-Shun rebellion against Tang (696-697). Tang retook Tarim from Tibet in 692; a Sino-Tibetan peace was made in 702. 
The Göktürks unsuccessfully fought the Ummayad Arab Caliphate for Transoxiana (712-713). Tibet and the Göktürk Khaganate fought China in the 720s; Tang and the Ummayad Caliphate fought the Göktürks and Tibet in the 730s.  The Uyghur Khaganate replaced the Göktürk Khaganate in 744 with Tang assistance. 
Forces of As-Saffah, the first Abbasid Caliph of Baghdad (r. 750-754), and of Xuanzong, the seventh Tang Emperor of China (r.712 -756) fought at the west-flowing Talas River AD 751 in a dispute over the control of Central Asia; the Abbasids were victorious. 
The Uyghur Khaganate became Tang’s patron in the An Lushan rebellion 755-763, while the Abbasid Caliph al-Mansur sent Arab mercenaries to aid Tang. The Abbasid Caliph Harun al-Rashid (r. 786-809) sent an embassy to emperor Dezong of Tang in c. 786/789 hoping for an alliance against Tibet, which expanded against both decaying states under Emperor Trisong Detsän (756-c. 797).  
The Caliphate and the Uyghur Khaganate fought Tibet during the rule of Emperor Tride Songtsän (799/804-815); Tibetan forces attacked Samrkand in Arab-controlled Transoxiana.  
Tibetan Emperor Ralpacan (r. c. 815-838) made a twenty-year peace with China 821/822.  Ralpacan is rumored in  Tibetan sources to have controlled Bengal, but the inadequate Bengali sources on the Pala rulers Dharmapala (r. 770/783-810/821) Devapala (r. 810/821-850/861) fail to notice him.
The Uyghur Khaganate was destroyed with Tang assistance in the 840s.  The Tibetan Empire broke into fragments after the assassination of Emperor Langdarma in 842 or 846.  The Abbasid Caliphate fractured slowly at first, then declined more swiftly after 861. Tang China’s last competent emperor, Xuānzong, died in 859, and Tang had disintegrated by 907, to be replaced by the Five Dynasties and Ten Kingdoms.  If there was indeed a four-power constellation, in the mid-9th century it fell apart.
However, the linkages between the khanates, Tang and Tibet seem far more profound and consequential than those between them and the Caliphate, whose control over its occasional eastward conquests was loose and challenged, and which occupied itself with wars of succession, wars with Byzantium, and secessionist struggles of Samanids, Hamdanids, Tahirids, Saffarids, Tulunids, Buyids, Idrisids, and Aghlabids.  
On the whole, and despite the collision at Talas, the westside-eastside connections of the 6th to 8th centuries seem too marginal and sporadic to be adjudged a significant linkage.  The Khanates, the Tibetan Empire and the Tang should all be seen as members of the eastside system; Talas, and its lesser predecessors and successors, should be seen as brief collisional interactions leaving no durable linkage.

The Mongols and the West
From 1246 to 1353, a number of intriguing exchanges took place between Popes and Kings on the west and Mongol Khans and envoys on the eastside.
Batu Khan, dispatched by Great Khan Ögedei (r. 1229-1241), conquered Russia and invaded Central Europe 1235-1241, demanding submission and devastating the renitent.  Holy Roman Emperor Frederick II (r. 1220-1250) and his enemy Pope Gregory IX (r. 1227-1241) both called for crusades against him, but fought each other instead.  Batu withdrew from Europe upon the death of Ögedei, so as to participate in the succession process.
Pope Innocent IV (r. 1243-1254), primarily concerned with the struggle against Frederick, in 1245 sent John of Plano Carpini with a message to “The Emperor of the Tartars” calling for him to become a Christian and cease invading others’ countries.  John was received in 1246 by Ögedei’s successor Güyük (r. 1246-1248), who sent him back with a letter claiming to rule the world and demanding that Innocent come and submit or be treated as an enemy.  A similar exchange of letters took place in 1247 between the papal envoy Ascelin of Lombardy and the Mongol commander in Persia. Mongol envoys returned with Ascelin. They met Innocent in 1248 and received a papal letter repeating his earlier adjurations; but in the interim, Güyük had died.
A more operational interchange took place between King Louis IX of France (St. Louis) and Eljigidei, Güyük’s Mongol commander in Persia (1246-1251/2).  Louis was embarking upon the very unsuccessful Seventh Crusade (1248-1250, against Ayyubid Egypt), and Eljigedei proposed (1248) synchronized attacks by Louis and the Mongols, against Egypt and Abbasid Baghdad respectively. In early 1249, Louis sent Andrew of Longjumeau with a letter for the (now deceased) Güyük; he was received by Güyük’s widow, the regent Ogul Qaimish (r. 1248-1251).  She returned a reply (received 1251) demanding annual tribute of gold and silver and threatening genocide if refused; no military cooperation was discussed by Ogul Qaimish, and for Louis it was now irrelevant, as he had lost his army in 1250, as it would soon be for Ogul Qaimish, who was killed in 1251 during the Mongol succession struggle that elevated Möngke (r. 1251-1259) as Great Khan.
Louis next (1253) sent William of Rubruck to convert the “Tartars” to Christianity and establish an alliance against the Muslims. Möngke, occupied with invading Korea, Dali, and India, received William in 1254 and sent him back, declining conversion and proposing peaceful cooperation.
Möngke in 1254 dispatched his Christian vassal king Hethum I of Lesser Armenia (r. 1226-1270) calling for Christian kings to sunmit as vassals to the Mongols and join them in fighting the Muslims.  Few joined the Mongols in destroying the Abbasid Caliphate of Baghdad in 1258.
The Mongols were disastrously defeated by Mameluke Egypt at Ain Jalut in 1260. Möngke was succeeded in name as Great Khan by Kublai Khan (r. 1260-1294). Kublai  was devoted to eastside expansion, conquering Song China (succeeding 1279), Japan (failed 1274 and 1281), Vietnam (failed 1284-1285; enforced suzerainty 1287-1288), Tibet (succeeded 1291), Burma (enforced suzerainty 1287), and Java (failed 1293).  During his khaganate, the Westside elements of the Mongols—the Golden Horde in the northwestern Mongol conquests (especially Russia) and the Il-Khanate in the Mongol southwest (Persia), as well as the centrally located Chagaitid Khanate—slowly became functionally independent and rival states.  Kublai became functionally the emperor of China, where he formally established the Yuan Dynasty in 1271.  He sought deeper control over the Mongol west, and a war (Kaidu-Kublai War, 1268-1301) ensued, ending with the nominal suzerainty of Kublai’s Yuan successor Temür (r. 1294-1307).  When the Chagatai khanate split into a western part in Transoxiana and an eastern part in the Tarim, both becoming statelets so weakly linking eastside and Westside as to be inconsequential. 

The Mongols and India
Genghis Khan’s Mongols chased Jalal-ad-Din, the last Khwarezmshah, into the Punjab, defeated him there, and withdrew (1221-1225).  Ögedei’s Mongols invaded northwest India again in 1235-1241, defeated local opposition, destroyed civilians, and withdrew, leaving Kashmir subjugated (1235-1241). Möngke’s Mongols restored control over revolted Kashmir (1254-1255); his brother Hulagu installed a client in Sindh (1257-1258).  These interactions at the Indic margin may be seen as a sideshow of the far more serious Mongol attempt to unite eastside and Westside.
As the Mongol Empire fractured, the Chagatai Khanate repeatedly invaded India 1292-1327, often plundering and extorting, but never conquering. Chagatai was marginal as among southside, eastside and Westside.

The Ming and the West
Ming admiral Zheng He (1371-1433/5) commanded seven voyages (1405-1433) from Nanjing, China, that proceeded along extant seas-trade routes and repeatedly reached the southwest coast of the Indic system and the Persian port of Hormuz, as well as “Mecca” (sc. Jeddah), and places in the Southeast Asian and East African systems.  Gifts were exchanged, those received designated as “tribute,” and some envoys brought to China to pay respects.  The voyages were stopped as unnecessary and costly.  No real political linkage, still less a durable linkage, was created thereby.  (See also “Timur,” below.)

Safavids, Ottomans, Uzbeks and Mughals
The Safavid Persian empire was a notable Westside power under its Shahs Ismail I (r. 1501-1524), Tahmasp (r. 1524-1576), Abbas I the Great (r. 1588-1629), and Abbas II (r. 1642-1666).  It was preoccupied with Westside wars and rivalries with the Ottoman Empire, the Uzbeks and Russia, and with internal disputes; but there were southside-westside encounters of some note.
Shah Tahmasp helped the refugee Mughal Emperor Humayun recover his throne in 1555, and received Kandahar as a reward. Humayun’s successor Akbar, through a 1586 treaty of neutrality with the expanding Uzbek power, was able to take Kandahar from Persia in 1590.  Abbas II went to war (1622-1623) with Akbar’s successor Jahangir, and took Kandahar.  Jahangir contemplated alliance with Ottoman Sultan Murad IV(at war with Persia 1623-1639) against Persia, as did his successor Shah Jahan, who sent an embassy that exchanged gifts, and seized Kandahar in 1638.  Abbas II recaptured it in 1648-1649 and held it against Mughal attacks in 1651-53.

Mughals, Marathas, Ming and Qing 
India’s Mughal dynasty (fl. 1506-1707) and its strongest immediate successor, the Marathas (fl. 1674-1818), were fully occupied in attempting to control India, although there was a war involving Tibet, Ladakh and the Mughals (1679-1684).
China’s Ming (1368-1644) and Qing (1644-1912) dynasties were preoccupied with wars in all directions except southside: the Ming with Mongols to the north, Manchus to the northwest, Japanese in Korea, the Qing—until European arrival in force--with Mongols to the northwest, Taiwan and Vietnam. However, the Qianlong Qing Emperor of China invaded Burma four times (1765-1769), but without success; he thereafter desisted. In 1788-1793, Nepal invaded Tibet, by then under Qing protection, but was driven out by Qing and signed a vassalage treaty, not enforced.
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APPENDIX IV. BRIDGE STATES?
Various social formations, more or less nucleated, more ort less sedentary, more or less politically integrated, and more or less politically connected to the systems trio, have existed in their borderlands near and around the Barrier.  Their linkage role needs to be assessed.
BMAC.  A settled Middle Bronze Age urban or proto-urban society (Bactria-Margiana Archaeological Complex or Oxus Civilization) existed in Central Asia c. 2300-1700 BC. Gonur Tepe, Namazga-Tepe and Altyn-depe, all in Turkmenistan, have a plausible claim to city-size and may therefore constitute a “civilization.” But the political structure of this putative civilization remains to be reconstructed, and it appears to have died off in the mid-2nd millennium BC. For the present, it cannot be brought within the scope of our inquiry, though intriguing questions do exist. 
Several points are, however, worth noting. The alleged Xia Dynasty of the Yellow River valley is roughly located somewhere between 2205 BC (earliest date calculated from traditional chronology) and 1558 BC (latest date from Bamboo Annals).  The alleged reach of the Xia goes no farther west than the North China plain; 
In Mesopotamia the BMAC period overlaps important states and empires from Sargon of Akkad through 3rd Dynasty Ur and Old Assyria to Hammurabi of the First Babylonian Dynasty.  The Mesopotamian dynasties are not known to have reached eastward politically beyond the Tigris basin.  
The Indus valley period of Indic civilization (c. 3300-c. 1300 BC) overlaps BMAC.  There was an Indus-culture trading colony at Shortugai on the Oxus; but no political reach of the Harappan state or states over the Barrier to BMAC has as yet been shown. And at present there is no evidence that an Oxus Civilization formed part of a political network with a Yellow River state, a Mesopotamian empire, or an Indus polity.
The Chariot peoples. The lightweight horse-drawn spoke-wheeled chariot apparently first appears northside in the steppe belt by c. 2000 BC, reaches the Westside via the Hittites by the 18th century BC, the southside (Indus basin) via Indo-Aryans by the Rigveda epoch c. 1500-1200 BC, and the eastside, perhaps via Proto-Indo-European “Tocharians” by c. 1200 late in the Yellow River Shang dynasty.  Technology clearly crossed or evaded the Barrier, but there is no evidence of inter-system political linkage associated with the technological diffusion.
Indo-Greek Kingdoms (180 BC-AD 10, fl. c. 130 BC). A Greco-Bactrian dynast successfully invaded India 180 BC, but his dynasty lost Bactria to the usurper Eucratides I (r. c. 171 BC-145 BC), and founded an “Indo-Greek kingdom” while failing to reconquer Bactria and repelling Greco-Bactrian invasions. The Indo-Greeks became important in Indic politics, their most successful ruler, Menander I (r. 165/155-130 BC) launching invasions eastward and southward, but the kingdom broke up and fell into civil war after his death and were displaced by the Indo-Scythians.
Indo-Scythians (c. 110 BC-12 BC, fl. c. 25 BC). Scythians (Sakas), Eurasian steppe nomads from the 9th to the 1st centuries BC, but pushed southward by the Xiongnu, Wusun and Yuezhi, Scythians invaded the Parthian empire, as noted; repelled by Mithridates II, they moved on, and invaded South Asia. Maues (r. 85-60 BC) briefly established an Indo-Scythian power in northwest India, subduing Indo-Greeks, who however rose again after him; Azes I (r. c. 48/47 – 25 BC) had another notable but fugitive success. The Indo-Scythians then in their turn fell under the domination of Indo-Parthians and then Kushans.
 “Indo-Parthians ” (“Pahlavas,” c. 20 BC–c. 130 AD, fl. c. 15 BC). A Parthian imitator, Gondophares I (r. c. 20 BC-10 BC), seems to have taken over a collection of northwest Indian vassal states from the Indo-Scythians; this hegemonic empire broke up after his death, and fell to the Kushans
 “Kushans” (fl. AD 30-225). Kushans were one of five segments of the Yuezhi who had fled southward before the Xiongnu and drove Scythians before them. From the mountains of Badakhshan (NE Afghanistan and Tajikistan), Kushan conquerors expanded southward into present Afghanistan, Pakistan, and Northern India. About AD 84-120 Kushans contended with Latter Han for hegemony in the Tarim Basin, apparently achieving it toward the end of that period.  The Kushans apparently ruled in the west end of the Eastside (Tarim Basin), the east end of the Westside (Oxus Valley and Fergana), and northern India (Indus and Ganges Valleys), perhaps simultaneously.  It is unclear how strong the imperial links between the various Kushan territories, and they do not seem to have been durable.
 “Indo-Sassanids” (“Kushanshahs,” fl. c. 250-410, 556-650/1 AD). Apparently Sassanid Persian nobles ruled as more or less autonomous governors in Bactria and Gandhara, often succeeding to the Persian throne; their tenure was evidently interrupted by “Hephthalites” c. 410 and ended by forces of the “Rashidun” Arab Caliphate c. 650/1.
“Hephthalites” (fl 5th to mid-6th centuries). “Hephthalites” is one of perhaps two dozen labels (e.g.“White Hun,” “Huna”) applied to some or all of a semi-nomadic collectivity that seized Bactria AD 420, and then fought Sassanid Persia, unsuccessfully in 427, but after having intervened (457-459) to enthrone the Sassanid Emperor Peroz I (r. 459-484),  they then twice (454, 475) defeated and ransomed him, and at last killed him (battle of Heart, 484). Hephthalite armies are seen unsuccessfully invading India in 455, in Sogdia in 478 and in Dzungaria and the Tarim basin in 493 and 508. Sassanid Emperor Balas (r. 484-488) paid tribute to the Hephthalites, who nonetheless overthrew him and installed Kavadh I, whom they later restored after a Persian coup displaced him: thus his two reigns, 488-496, and 498-531.  Hephthalite armies attained control over Central Asia while never apparently forming a unitary state, until the Sassanid Emperor Chosroes I (r. 531-579) allied with the rising Göktürk power to defeat the disorganized Hephthalites and seize and divide the Oxus Valley in 557. 
The Hephthalite horde-armies hived off the better organized so-called Kushano-Hephthalites (“Hunas,” fl. AD 480-532). These Huna emperors Toramana and  Mihirakula ruled part of northwest India in the late 5th and early 6th century; Mihirakula would likely have been the Hephthalite ruler of 40 kingdoms visited in 519 by the Chinese pilgrim Song Yun.  Except for the brief Kushano-Hephthalite rule in India, “empire” seems too strong a descriptive term for what was more likely a heterogeneous conglomeration of tribal armies and kingdoms inclined to ride off in all directions.  Scattered Hephthalite principalities survived the defeats of the Hunas and at the Oxus.
Saffarids (fl. 861-901).   Ya'qūb ibn al-Layth al-Saffār (r. 861-879) and his brother Amr ibn al-Layth (r. 879-901) established as considerable state in Khorasan, eastern Persia, Fars and Herat, but failed to conquer Transoxiana, in which attempt the saffarid power was extinguished.  They controlled Sindh, but almost all their activity and connections were Westside.  
Ghaznavids (fl. 977-1030).  Sabuktigin (r. 977-997) created a domain in today’s Afghanistan, and ruled to the Indus; his son Mahmud of Ghazni (r. 998-1030) ruled Sindh, established client states in northwest India, and raided and looted north India on an annual basis. The later Ghaznavids fell into civil strife and division, losing their Persian lands to the Seljuks by 1040 and their Indian lands to the Ghurids in 1186.
Ghurids (fl. 1163-1206). The Ghurid Sultanate at its peak controlled Afghanistan and the Indus and Ganges basins.  Its rulers at its zenith were Ghiyath ad-Din Muhammad (r. 1163-1202) and his brother, viceroy and successor Mu'izz ad-Din (“Muhammad of Ghor,” r. 1202-1206).  It is not clear that the Ghurid Sultanate was ever a unitary entity; during the life of Ghiyath ad-Din, he managed Afghanistan and fought Turks and Khwarezmians, while Mu’izz as-Din conquered in India; after the death of Ghiyath, Mu’izz fiought Khwaerzm and allied with Kara-Khitai, but left India in the hands of his slave-generals. After the death of Mu’izz, his territories were divided arming his slaves; one of them, Qutb Qutb-ud-Din Aibak, became independent ruler of the Delhi Sultanate, founding its Mamluk (or Slave) Dynasty, and failed in an attempt to conquer Ghazni. There was a Westside-southside linkup in the Ghiyath-Mu’izz pair, and then in the person of Mu’izz, but it is hard to see much of a durable intersystem connection beyond the personal. 
Timur/Tamerlane (fl. 1380-1405).  The conqueror Timur waged his wars and established his rule mainly on the Westside, in Persia, Mesopotamia and the Caucasus; he conquered Delhi in 1398 but destroyed it and departed.  At his capital Samarkand, envoys of the Hongwu and Yongle Emperors of Ming China arrived in 1394, 1397 and 1404, in pursuit of the acknowledgment of Ming suzerainty, which they did not secure from Timur, who imprisoned them. Timur prepared to invade China, but died enroute.  His empire divided.
Shah Rukh Mirza, Timur’s successor in Persia and Transoxiana, (r. 1405-1447), established more traditional relations with Ming.  Chen Cheng led Ming missions to Shah Rukh in 1414, 1416 and 1420; Ghiyasu'd-Din Naqqash recorded a Timurid mission of 1419-1422, filled out by merchants, returning with much commercial information.  No wars, war menaces, or dominance ensued from either.