Steppe Effect
Discussion
Peter Turchin:
"The gist of the argument is as follows. The Great Eurasian Steppe stretches some 7,000 km from Manchuria to Wallachia. After the Eurasian pastoralists developed horse riding around 1000 BCE (Turchin et al. 2016), the steppe became home to nomadic horse archers who, despite their relatively small numbers (in comparison to the neighboring agricultural regions), wielded enormous military power. This power was due to their plentiful supplies of horses, which were the most important military “technology” during the ancient and medieval eras; to their high military participation rate, as all adult men were warriors; and to their riding and archery skills resulting from their nomadic pastoralist way of life. This preponderance of military power, coupled with a perennial need for agricultural products, created a high potential for conflict and warfare on the frontiers where the steppe abutted agrarian regions. In The Perilous Frontier Thomas Barfield (1989)advanced a “shadow empires” model, according to which steppe pastoralists formed confederations to obtain the needed products from adjacent agrarian empires by raiding, extortion, or forced trade whose terms favored the steppe dwellers.
I added to Barfield’s model by arguing that just as the presence of sedentary empires exerted a pressure on the steppe to unify, the causality also flowed in the opposite direction: aggressive imperial confederations in the steppe exerted pressure on farming societies to scale up their polities. This autocatalytic process of mutual causality resulted in a recurrent formation of “mirror empires” on both sides of the steppe frontier (Turchin 2009). In addition to this direct effect, the steppe also exerted an indirect influence that radiated out through Afro-Eurasia. Because cavalry (first horse archers, later supplemented by heavy cavalry) was extremely effective at prosecuting war, agrarian polities eagerly adopted it and used it in wars with their neighbors. As a result, cavalry gradually spread throughout Afro-Eurasia, and later to the New World. The Steppe Effect explains why the incidence of mega-empires (territorial polities controlling a territory of 1 million km2or more) is very high on the steppe frontiers—the contact and conflict zones between nomadic pastoralists and settled agriculturalists. Incidence of mega-empire rapidly declines with distance from the Eurasian Steppe. It also explains why the European states (at least after the fall of the Roman Empire) were an order of magnitude smaller than in China—Western Europe was insulated from the Steppe Effect by eastern Europe (which gave rise to several mega-empires, the most recent of which is Russia). As Scheidel reviews, the Steppe Effect is supported by a number of additional lines of argument. For example, with a single exception, all unifications of China originated in the northwest or north—in other words, from the steppe frontier, areas that due to their climate had much less productive agriculture than, for example, the lush Yangtze delta."