A late-Holocene pollen record from the western Qilian Mountains and its implications for climate change and human activity along the Silk Road, Northwestern China

The sparsity of long-term reliable climatic records hampers our understanding of human-environment interactions in the semi-arid Hexi Corridor, NW China. Here, we present a late-Holocene pollen record from a small alpine lake, Tian'E, in the western Qilian Mountains. The chronology is provided by nine accelerator mass spectrometry (AMS) C-14 dates from terrestrial plant remains. The ratios of Artemisia and Amaranthaceae (A/C) are used to reconstruct the history of regional humidity: An unstable climate occurred during 1530-1270 BC; there were three relatively wet periods, at 1270 BC-AD 400, AD 1200-1350, and AD 1600-present; and there were two dry periods, from AD 400 to 1200 and from AD 1350 to 1600. Comparison with tree-ring data indicates that continuous droughts were responsible for the abandonment of several archaeological sites and ancient cities in the region, including the major city of Dunhuang, which was abandoned in AD 1372 and AD 1524 for nearly 200 years.