One consequence is that frontier peoples bury their differences and help one another.
Thus, the 'meta-ethnic faultlines' between civilisations are 'asabiya incubators' from which new empires spring. This, he says, was how a small group of Cossacks was able to defeat a much larger army of Tatars in Siberia in 1582. Using modern understanding of how co-operative behaviour develops in groups of organisms, Turchin's models suggest that asabiya becomes particularly strong on the frontiers of empires, where two civilisations confront one another. He calls this asabiya, an Arabic word denoting 'mutual affection and willingness to fight and die for each other'. Turchin believes these empires were the product of one factor: social cohesion, the willingness of groups to co-operate against opponents. But War and Peace and War is even more ambitious for it attempts to explain some of history's grand narratives: the rise and fall of Rome, the expansion of medieval European powers, the Russian conquest of Siberia.
