A review by ochers
War and Peace and War: The Rise and Fall of Empires by Peter Turchin

3.0

Why do empires rise and fall? Asabiya - or cohesion, coined by Ibn Khaldun and appropriated by Turchin. He argues that empires form when under tension via adversaries on the border - when these adversaries are of distinctly opposite 'meta-ethnicities', this tension tends to act as a stressor which can enhance asabiya, leading to the formation of an empire. The strength of this empire is, according to Turchin, correlated with asabiya - which forms as highlighted above.
The hypothesis is interesting - Turchin's use of historical examples such as the Cossacks, and the Roman Empire, serve as crucial points. However, the distinct lack of data, and his (somewhat) reliance on 'cliodynamics' were distinct weaknesses.