Climate as a factor for Neolithic cultural collapses approximately 4000 years BP in China

Although archaeological findings show the synchronous collapses of major well-documented Chinese Neolithic cultures around 4000 cal. yr BP, the driving mechanism for the phenomenon is still unclear and debatable. Spatial climatic features in China spanning this time period suggest a generally cold-dry setting. This is evidenced by 130 well-dated geological records at 97 sites located in climatically and topographically diverse regions, with occurrences of some extreme hydrological events like severe floods in the Chinese Loess Plateau, and in basins of the lower Yellow River and the middle-to-lower Yangtze River. The weakening of the Asian Summer Monsoon (ASM) since the mid-Holocene would have made Neolithic subsistence living unfavourable by decreasing the warmth and wetness in arid and semi-arid regions. However, it might not have been the sole factor that destroyed the Neolithic cultures in the vast territories of China ca. 4000 cal. yr BP. Environmental alterations in the major cultural territories of China reacted in response to precipitation anomalies caused by high variability of the ASM and the westerlies, which were modulated by centennial- to inter-annual- scale driving factors such as solar insolation, the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO) and El Niño-Southern Oscillations (ENSO). This most likely accounted for the nearly synchronous Chinese Neolithic cultural collapses.