Escape From Rome

by Walter Scheidel

  Shape, Isolation, and Scale

  Its relatively square shape makes East Asia more compact than Europe. When Rome turned the elongated Mediterranean Sea into its imperial core—useful for low-cost transfers but bereft of people—outward power projection created very extended frontiers. If we discount the Atlantic and ignore the arid African frontier, the Roman empire still had to protect close to 6,000 kilometers of potentially contested borders. Even though the various strands of the Great Wall add up to much more than that, the effective length of the frontier from Korea to the far end of Gansu was only about half the Roman value. For most of the time, this was the only front that really mattered, whereas Rome faced serious challengers from different directions.18

  Other features arguably mattered less. China was objectively more isolated than Europe. Joseph Needham characterized China as “an amphitheatre facing the Pacific Ocean”—and, he might have added, for a long time with little of note out there. Europe, by contrast, has always been closely connected to the Middle East and North Africa region. There is no clear physical boundary between the Atlantic in the west and the Hindu Kush and the east Iranian and Balochi deserts in the east, and even the latter cannot rival the Tibetan highlands and the Taklamakan desert.

  In a very basic sense, this made hegemonic empire more feasible in East Asia: no one power could hope to control all of temperate Eurasia from the Atlantic to eastern Iran. When the Umayyads tried, the extreme east–west stretch of their realm invited fraying from the edges. Much of the time, fragmentation within this space put pressure on less expansive empires. Yet the inverse did not necessarily apply: had isolation been a decisive feature, South Asia, which is just as isolated as China, should have been similarly united.19

  Finally, the spatial extent of state systems may also be relevant. Once again we need to be careful. Core China and Latin Europe are of comparable size. The geodesic distance from Seoul to Hanoi is the same as that from Lisbon to Warsaw (2,750 kilometers). The Chinese empire grew early on by expanding to the northwest: Kashgar, at the western end of Xinjiang, is 3,400 kilometers from Beijing and almost 4,400 kilometers from Seoul. Similar metrics apply to the early modern European state system once we include the Ottoman and Safavid empires: Lisbon lies more than 5,400 kilometers from Isfahan. Even if we stick to Christian societies, Moscow is 3,900 kilometers away.20

  If we merely looked at these figures, we might conclude that European and Chinese state-building and competition played out on a similar scale. But there was one big difference: unlike in East Asia, the European state system kept growing over time. Korea and northern Vietnam had been part of the Chinese ecumene since the Western Han period, and with minute exceptions—Mongol incursions into Southeast Asia at the end of the thirteenth century and the Japanese invasions of Korea three centuries later—most of Southeast Asia as well as Japan effectively remained outside the China-centered political-military network even as more stable polities developed in its periphery.

  To the north and west of Italy, ancient Rome had occupied a space that lacked prior state structures. Its success forever changed the political landscape by extending state-ness, for want of a better term, into continental Europe. At first, Rome’s fall did little to change the scope of this process: the successor states barely extended beyond the old Rhine–Danube frontier, and only Charlemagne regained what Augustus might once have projected as Rome’s Elbe frontier.21

  What Peter Heather calls “the ancient world order in western Eurasia: a dominant Mediterranean circle lording it over an underdeveloped northern hinterland” was finally overcome in the Early Middle Ages. Alongside literacy, state-building spread eastward and northward, a grand move “towards greater homogeneity right across the European landmass.” Slavic peoples played a central role. In the ninth and tenth centuries, they established large if fluid polities, driven in part by German eastward predation. The tenth century in particular witnessed a massive extension of political and social hierarchies beyond the old civilizational cores, into Poland, Bohemia, Hungary, Rus’, and coastal Scandinavia. Much of Central and Eastern Europe filled up with increasingly ambitious regimes and incipient states or hegemonies. By 1000, recognizable polities stretched all the way to the Volga.22

  External inputs contributed greatly to this process, which did not take the form of imperial conquest but was spurred on by decentralized initiatives backed by military, clerical, and mercantile elites—decentralization that reflected the fractures of their places of origin, most notably Germany. Where an aristocratic diaspora of castle-building knightly cavalry led, farmers and burghers followed. Thanks to the widespread replication of Western European structures—towns, churches, and noble estates—this expansion did not create core-periphery relations but simply enlarged the reach of a certain set of institutions eastward. As a result, as Heather puts it in not quite politically correct bluntness, “Barbarian Europe was barbarian no longer.”23

  What we are concerned with here is not “barbarousness” but statehood, and in that respect homogenization made major headway: in Europe, the spatial extent of state-level political organization grew from roughly three million kilometers in 800 to maybe three times as much in 1600. Aside from northern Scandinavia and northern Russia, most of this enlargement took place during the first half of that period. According to one estimate, Latin Europe alone doubled in size between 950 and 1350, and by then boasted the largest cluster of similarly organized polities anywhere in the world.24

  It is true that it took some time for this expansion to have a major impact on interstate competition within Europe. Although Bohemia played a significant role in the affairs of the German empire from the thirteenth century onward, conflict among the Great Powers of the Iberian peninsula, France, England, Germany, and Italy unfolded without eastern or Nordic interference, a situation that changed only with Sweden’s intervention in the Thirty Years’ War. Before the Napoleonic Wars, Russia, facing Swedes and Poles alongside Ottomans and Tatars, exercised little tangible influence on Western Europe.

  In that sense, the medieval expansion of the European state system did not directly contribute to the stabilization of polycentrism in its Latin core. The mere existence of Central and Eastern European states, however, made this fragmentation more robust in that it provided additional checks to any imperial ventures that might otherwise have been launched. When Russia finally intervened in the early nineteenth century, its military power proved all the more decisive in preserving Europe’s balanced state system.25

  For the most part, Europe’s colonial empires overseas played a more indirect role. While Spain’s access to American silver overtly threatened the balance of power, this threat also helped galvanize resistance that ultimately shored up political polycentrism. Overseas resources were not generally critical for maintaining the European state system, even if England was able to draw on global assets in its successful containment of France after 1800. In the end, it was the size of Europe’s sphere of competitive integration that mattered most.

  Expansions such as those into Central, Northern, and Eastern Europe (or overseas) did not occur in South, Southeast, or East Asia. Indian states were largely confined to the subcontinent. Their principal political-military interaction zone with the outside world was a relatively narrow frontier to the northwest, made permanent by formidable natural obstacles. Much the same was true of China with its steppe frontier, and Southeast Asia was even more tightly hemmed in by mountain ranges. There was generally little if any scope for substantial offshoots that could have contributed to political fragmentation.

  What, then, does geography tell us about state formation? By a number of counts, the East Asian environment favored large-scale empire and hegemony: limited articulation, considerable compactness, weaker internal obstacles, and a rich, “natural” core that could be further integrated with the help of manageable human inputs. Europe, by contrast, was much more segmented by mountains and the sea, and lacked large concentrations of natural resourc
es. South Asia scored somewhere in between, and the same applies to the Middle East and North Africa, with their mixture of fertile river basins, highland plateaus, and arid zones.

  What is at stake here is emphatically not the old bugbear of “geographical determinism.” Geography is not destiny, but it does tilt the field in favor of particular outcomes by making them more or less costly and therefore more or less likely to occur in some parts of the world than in others. It would be self-defeating to approach the problem of the First Great Divergence without taking account of the physical environment.26

  In fact, it is imperative to expand our analysis beyond coastlines, rivers, mountains, and soils to consider a more specific and arguably even more powerful factor: proximity to the steppe. State formation was not merely shaped by spatial scale and the properties of the terrain upon which it unfolded. It was also strongly influenced by conditions outside those settled zones where agriculturalists produced the surplus that fed cities, armies, officials, and courts.

  ECOLOGY

  The Steppe Effect

  The vast Eurasian Steppe, a belt of continuous grass- and shrublands, once stretched more than 7,000 kilometers from Manchuria to Wallachia (figure 8.3). Its vegetation cover and gentle relief afforded considerable ease of movement to riders and livestock. Northern China abuts this zone and was the locus of intense imperial persistence. Latin Europe, situated at greater remove, was not. The Middle East and North Africa region, bordering on the Eurasian steppe and several more arid frontiers, repeatedly gave rise to large empires. So did northern India, more detached from the Eurasian steppe but exposed to it through links on its northwestern flank. Conversely, state formation generally unfolded on a smaller scale in more sheltered southern India and Southeast Asia. Were these correlations coincidental, masking diverse causes, or do they reflect a broader dynamic of causation in imperiogenesis?27

  FIGURE 8.3   The Eurasian steppe.

  Recent scholarship supports the latter interpretation. In 2009, Peter Turchin observed that up to 1800, except for modern European overseas colonies, most empires that covered at least 1 million square kilometers (a convenient metric equivalent to three-quarters of a percent of the earth’s land surface outside Antarctica) emerged in close proximity to a steppe frontier. My own revised and updated version of Turchin’s survey shows that 62 out of 73 such polities more or less clearly belong in this category. No fewer than 54 of these 63 developed either in or very close to the Eurasian steppe. We must not put too much weight on precise numbers: some of these empires were effectively continuations of previous ones and need not be classified as discrete cases. Even so, the overall pattern is robust.28

  The observed distribution cannot equally well be explained with reference to natural endowments. Latin Europe, southern India, and Southeast Asia, large areas that were equipped with enough people and natural resources to support large-scale state formation but were distant from the steppe, rarely produced similarly substantial empires. Away from the steppe, empire-building on this scale remained limited to just a few cases: the Roman and Carolingian empires in Europe, the Angkorian empire in Southeast Asia, and the Inca empire in the Andes. Among these four, the Frankish and Khmer polities barely cleared the size threshold, and the former proved rather brittle. Only Rome could rival the largest agrarian empires of the Middle East and South and East Asia in terms of both heft and longevity.29

  This geographic clustering is best captured by maps. Figure 8.4 pinpoints the source regions of traditional Old World empires in excess of 1 million square kilometers. The grid pattern in figure 8.5 visualizes the odds of being part of such a polity: the darker the color, the longer a particular area had been ruled in this way. Taken together, these two maps reveal a distinctive pattern. Large empires were concentrated in East and Central Asia, the Middle East, and Egypt but were rare in Europe, southern India, and Southeast Asia. Northern India occupies an intermediate position. I discuss these regional specifics later in this section.30

  An alternative measure, focusing on population rather than territorial extent, controls for the proliferation of steppe empires that could be extensive but sparsely inhabited. This approach yields similar results. Up till 1800, thirty-two traditional land empires claimed at least 8 percent of the world population at the time, a threshold that empirically allows fairly clear demarcation from lesser cases. Twenty of these originated at or close to steppe frontiers, and another seven at somewhat greater remove. In this sample, the Roman empire was once again the principal outlier.31

  Whichever way we look at this, the global distribution of mega-empires reflects a “strong statistical regularity” as their incidence declines rapidly with distance from the Afroeurasian steppe zones. This allows us to advance a parsimonious working hypothesis: the scale and intensity of imperiogenesis were profoundly shaped by ecological features that drove state formation via intermediating proximate mechanisms.32

  FIGURE 8.4   Spatial distribution of the core areas of empires of at least 1 million square kilometers in Afroeurasia. Source: Adapted and expanded from Turchin 2009: 204, figure 1.

  FIGURE 8.5   Probability of being part of large polities (> 1 million km2) at 100-year intervals, 500–1500 CE (probability rising from medium gray = low, to black = high; light gray = zero). Source: Scheidel in press-b: figure 2.13(b). Data provided by James Bennett (University of Washington) on November 9, 2017, drawing on the data underlying Turchin et al. 2013: 16386.

  This hypothesis proceeds from the premise that antagonistic relationships between steppe pastoralists and settled agriculturalists precipitated scaling-up of state power and size in response to competitive pressures. In keeping with a wide range of scholarship on the drivers of state formation, this perspective privileges the role of intergroup conflict in the creation and evolution of powerful political-military entities.33

  It is also rooted in ecological fundamentals. Very broadly speaking—and this ideal-typical sketch accommodates a great deal of real-life diversity and hybridity—steppe peoples inhabited grasslands primarily as pastoralists who reared livestock, especially horses and sheep, even as they supplemented these activities with farming, foraging, and hunting. To varying degrees, this mode of subsistence favored a mobile lifestyle conditioned by seasonal movements and access to horses.

  Such groups found it hard or were even unable to produce many of the goods found in sedentary societies. In order to obtain such goods, they had to trade with, serve in the military of, or raid sedentary societies. Access to and facility with horses supported all of these pursuits. Cavalry warfare enabled steppe warriors not only to compensate for agriculturalists’ superior numbers but also to enjoy high mobility. Moreover, the nature of the steppe, lacking the numerous and vital fixed positions associated with settled life, made it easier to retreat from counterattacks. By combining flexible forward-striking power with great strategic depth, steppe forces were in a position to punch far above their demographic weight.34

  On the other side of the ecological divide, the economies of sedentary populations generated resources that were not only attractive to steppe groups but also could be used to build up massive military capabilities. These complementary differences and capacities created “fundamental structural incompatibilities” that could be managed in a variety of ways: open conflict was by no means the only option. Even so, over the long run, the ecological pressures of steppe life and rulers’ ambitions made periodic outbreaks of conflict more likely than not. For this reason alone, scaling-up held considerable appeal.35

  This idea has a long pedigree, associated with Owen Lattimore and other students of the steppe rim. It also represents a variant of Turchin’s “meta-ethnic frontier theory” that expects the strongest impulses for state formation to manifest along civilizational fault lines, such as diversity of religion, language, mode of subsistence, and intensity of warfare.36

  In his massive comparative survey of Old World macro-social development, Victor Lieberman argues
that the degree of proximity to the steppe split Eurasia into “exposed” and “protected” zones: “Insulation/vulnerability to Inner Asian occupation is the central criterion of protected zone/exposed zone status.” His “protected” areas include Southeast Asia, most of Europe, Japan, and Korea, the Himalayan region and Tibet, and coastal South Asia and Sri Lanka. China, continental South Asia, and Southwest Asia were much more exposed. In general, “protected” regions remained more isolated and produced charter civilizations later and with smaller polities than “exposed ones.” He identifies Inner Asian influences as the key coordinating agent behind this difference: for most of their history, and consistently so after 1400, the “protected” zones regions were sheltered from occupation by Central Asian nomads and generally led by indigenous elites.37

  FIGURE 8.6   Effective distance from the Eurasian steppe (by land). Source: Adapted from Ko, Koyama, and Sng 2018: 290, fig. 4.

  A region’s level of protection was mediated by three principal factors: proximity to the steppe by distance, the presence of barriers such as mountains and the sea, and links to the steppe (figures 8.6 and 8.7). For instance, it mattered that South Asia, albeit quite far away from the Eurasian grasslands and protected by the Himalayas, connects to Central Asia via river basins and shrublands. Western Europe was better shielded by the interposition of woodlands but faced a detached steppe bridgehead, the Pannonian plain, even if only on a modest scale.38