Weather Shocks, Sweet Potatoes and Peasant Revolts in Historical China

I use data covering 267 prefectures over four centuries to investigate two questions about historical China. To what extent did weather shocks cause civil conflict? And to what extent did the historical introduction of (drought resistant) sweet potatoes mitigate these effects? I find that before the introduction of sweet potatoes, exceptional droughts increased the probability of peasant revolts by around 0.7 percentage points, which translates into a revolt probability in drought years that is more than twice the average revolt probability. After the introduction of sweet potatoes, exceptional droughts only increased the probability of peasant revolts by around 0.2 percentage points.