War and Peace and War: The Rise and Fall of Empires

by Peter Turchin

The civilization zone is divided into states and empires, which are, in any case, normally quite good at defending themselves against nonstate societies. For one thing, the civilization supports much greater population densities than the desert, so the civilized armies tend to be larger than the “barbarian” ones. Civilizations also have technological advantages, such as fortifications, catapults, better arms, and armor. As long as the state keeps its internal cohesion, it is capable of defending itself against the nomads. (There are exceptions—nobody could stand against the Mongols of Chinggis Khan.) When the state loses its unity and falls into civil strife, however, it immediately becomes easy prey for Bedouins. Ibn Khaldun noticed that political dynamics in the Maghreb tend to move in cycles. When a state in the civilization zone falls into internal strife, it becomes vulnerable to conquest from the desert. Sooner or later, a coalition of Bedouin tribes is organized around one group with a particularly high asabiya. When this coalition conquers the civilization zone, it founds a new state there. The leading group establishes the ruling dynasty, while other Bedouins become the ruling class—the new aristocracy.