Hydroclimatic instability accelerated the socio-political decline of the Tang Dynasty in northern China.

Extreme flooding and prolonged, intensifying droughts have played a critical role in the rise and collapse of preindustrial states and empires worldwide, triggering cascading impacts such as crop failure, famine, and migration that undermined socio-political stability and economic resilience. We present a multicomponent hydroclimatic vulnerability model for crop supply networks to estimate the contribution of climatic stressors as one of several factors contributing to the decline of the late Tang Dynasty in northern China between 800 and 907 CE. We demonstrate that recurrent flooding and prolonged droughts, combined with an unsustainable shift in crop production from drought-tolerant millet to less resilient wheat and rice, led to harvest failures and food shortages during the cooler and drier climatic conditions of the late 9th and early 10th centuries CE. Intensifying raiding from competing polities and climatic extremes further affected grain supplies for the late Tang's northern military frontier and partly contributed to the sudden decline of the dynasty. Our results emphasize the importance of multicomponent environmental response models to understand historical transformations and provide new aspects of China's socio-political development during medieval times.