Climate-driven desertification contributed to the decline of the Ancient Silk 1 Road 2

18 The Ancient Silk Road played a crucial role in cultural exchange and commercial 19 trade between western and eastern Eurasia during the historical period. However, the 20 exchanges were interrupted in the early 16th century AD, in the Ming dynasty. Three 21 causes of the decline of the ancient Silk Road have been suggested: (1) the thriving of the 22 sea trade route following major geographical discoveries in the Ming dynasty; (2) 23 frequent incursions by the Oirat and Turpan kingdoms, or fighting in border areas; and (3) 24 climate change. In this study, new evidence from a sedimentary site in Dunhuang oasis, 25 together with analysis of historical archives, indicate that neither the sea trade route nor 26 the frontier wars were the tenable explanation for the decline of the ancient Silk Road. 27 However, the desertification event that caused by climate change might have played a 28 crucial role in the abrupt decrease of trade exchange on the ancient Silk Road around 29 1450 AD. XSW site in this study indicated that, extreme droughts and desertification 30 events occurred in the Dunhuang area post ~1450 AD and persisted for decades at least. 31 The desertification reduced the accessibility of the ancient Silk Road in this area, which 32 was responsible for a steep fall in the volume of trade as well as political chaos and mass 33 migrations. The final closure of the Jiayuguan Pass in 1539 AD and the abandonment of 34 Dunhuang city further accelerated the decline of the ancient Silk Road. 35