The possible climate impact on the collapse of an ancient urban city in Mu Us Desert, China

Tongwan City is one of the most famous and best-researched archaeological sites in China. By using palaeoclimatology proxy records from China over the last 2,000 years and archaeological/historical documents, we analyse the possible effect of climate on the collapse of Tongwan City, an ancient urban city of the Daxia state (AD 407-427). During Tongwan City's existence (AD 413-994), two severe cold and drought stages were recorded by both natural proxy data and the synthesis compiled from the historical documents. The first cold and drought stage occurred at about AD 420-550, with the lowest point centred at about AD 500. The second cold and drought stage occurred at about AD 780-950. These periods correspond to the times of climate deterioration, especially weak summer monsoons, which eventually resulted in the intensive desertification and collapse of Tongwan City.