Significance: This paper presents a new long speleothem δ ¹⁸ O time series from Xiaobailong cave in southwest China that characterizes changes in a major branch of Indian summer monsoon precipitation over the last 252 kyrs. This record shows not only 23-kyr precessional cycles punctuated by prominent millennial-scale weak monsoon events synchronous with Heinrich events in the North Atlantic, but also clear glacial–interglacial variations that are consistent with marine records but different from the cave records in East China. The speleothem records of Xiaobailong and other caves in East China show that the relationship between the Indian and the East Asian summer monsoon precipitation is not invariant, but rather varies on different timescales depending on the nature and magnitude of the climate forcing.

We developed a composite oxygen isotopic record of cave calcite for the last 1860 years based on three stalagmites from the Huangye Cave in eastern Gansu Province, northern China. The δ¹⁸O values reflect monsoon precipitation changes, with lower δ¹⁸O values representing higher precipitation and vice versa. Three intervals of high precipitation were identified at AD 138—450, AD 730—1200, and AD 1860—1960. Two intervals of low precipitation occurred at AD 1320—1410 and AD 1530—1860. The reconstructed monsoon precipitation variations correlate well with other records further east in the eastern Yellow River Basin, suggesting synchronous precipitation changes during the late Holocene in the semi-humid region of northern China on decadal to centennial scales. Peak periods of warfare in dynastic transition times, such as at AD 391—420, AD 601—630, AD 1111—1140, AD 1351—1380, and AD 1621—1650, correspond to sharp declines in precipitation or temperature in semi-humid northern China, indicating a strong connection between climatic and societal changes. Our study suggests that climatic deterioration in semi-humid northern China has played an important role in Chinese societal evolution.