I recently came across an interesting news article on Turchin and his theory of the rise and fall of civilizations:
. . . he argues the fluctuations in population of pre-industrial societies can be linked to periods of instability and civil war. His theory shows how population growth caused by increased prosperity can itself trigger such social instability, thus sowing the seeds of its own decline. This, says Turchin, is how civilisations and empires collapse. 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. Turchin believes these empires were the product of one factor: social cohesion, the willingness of groups to co-operate against opponents. He calls this asabiya, an Arabic word denoting "mutual affection and willingness to fight and die for each other".
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. This, he says, was how a small group of Cossacks was able to defeat a much larger army of Tatars in Siberia in 1582. Thus, the "meta-ethnic faultlines" between civilisations are "asabiya incubators" from which new empires spring. Here, either you unite or you die.
One consequence is that frontier peoples bury their differences and help one another. The downside is that they exaggerate factors that distinguish them from their foes, who become subhuman barbarians, heathens or infidels. Sounds familiar? Turchin points out how, after September 11, 2001, a US radio host referred to Arabs as "nonhumans" and claimed that "conversion to Christianity is the only thing that probably can turn them into human beings". The US has all the hallmarks of an empire, Turchin says, and it is one in which asabiya is showing its dark side in nationalism and xenophobia. "Today the most violent clash of civilisations occurs on the meta-ethnic frontiers of Islam with the Western, Orthodox, Hindu and Sinic civilisations," says Turchin. But if his theory is right, it will be in these conflict zones, such as the borders of Europe, that the next great empires will arise.