Climate Shocks, Political Institutions, and Nomadic Invasions in Early Modern East Asia

While a large literature argues negative climate shocks can trigger conflicts, recent findings suggest moderate climatic conditions lead to war. This article proposes a conditional theory by incorporating political institution as a moderating variable. I argue that, under the impact of negative climate shocks, centralized societies can mobilize more resources for war, compared to decentralized societies. Thus, the former is more likely to resort to well-organized plundering to address the scarcity problem caused by detrimental climate shocks. Besides, centralized societies have little incentive to plunder when the climatic conditions are moderate, as they can collect taxes regularly through centralized institutions. A comparison between the more centralized Manchurian and the less centralized Mongols on their conflictual behavior serves as an empirical test. I find that temperature was negatively associated with the probability of Manchurian invasion after they embraced centralization but had a positive effect on the likelihood of Mongol invasion.