The relationship between interannual dry/wet changes and nomadic wars in the Hexi Corridor region of China during the period 241–1912 A.D.

The link between climate and war has long been a topic of great scientific and social interest. In this study, we investigate the influence of climate on warfare in China’s Hexi Corridor region since 241 A.D. Using the superposed epoch analysis of tree-ring data and historical war data, we observe a notable correlation between interannual dry-wet variations and wars instigated by nomadic groups in the Hexi Corridor. However, this relationship is dynamic and influenced by the region’s relative unity. During periods in which the Hexi Corridor was ruled by multiple regimes, wars tended to follow dry climatic conditions, which may be due to the fact that unusual drought during these periods likely heightened competition for resources and land. Conversely, during times of regional unity, wars were more likely to occur when climatic conditions were wet because the expansion of rangelands and the accumulation of resources helped fuel the nomads’ outward conquest. These findings underscore the complexity of the relationship between war and climate change. To gain a more comprehensive understanding of this relationship, continuous, high-resolution historical temperature and humidity datasets with broader and more uniform coverage are needed across multiple regions. In addition, collecting and examining disaggregated historical war data for regions with distinct characteristics is essential.