Climate shocks, dynastic cycles and nomadic conquests: evidence from historical China

Nomadic conquests have helped shape world history, yet we know little about why they occurred. Using a unique climate and dynastic data set from historical China dating from 221 BCE, this study finds that the likelihood of nomadic conquest increases with less rainfall proxied by drought disasters, which drove pastoral nomads to attack agrarian Chinese for survival. Moreover, consistent with the dynastic cycle hypothesis, the likelihood of China being conquered increases with the number of years earlier that a Chinese dynasty had been established (and hence was weaker, on average) relative to a rival nomadic regime. These results survive a variety of robustness checks.