Crop dispersal along the prehistoric highland silk road on the Tibetan Plateau

Previous studies demonstrated that the farmers spread into the Tibetan Plateau (TP) and permenantly settled there around 3600 yr cal BP, taking the ways on the northeastern edges of the TP and bearing the western crops of barley, and sheep. But, other studies argued the earlier permenant settlements or different ways to spread into the central TP. Meanwhile, the Yarlung Tsangpo River regions in southern TP, are considered to be one of the important routes for culture dispersal and human migration, jointing Tibetan Empire, Tang Dynasty and states in South Asia in history period, were proposed as highland silk road. However, the role of this route in prehistorical culture exchange and human colonization on the TP remains unclear, due to the scarce of archaeological work in these regions.

Systematic surveys along the Yarlung Tsangpo River regions had carried out in last two years. Charcoals and charred seeds were floated from the cultural layers in 31 sites and 60 new carbon-14 dates had been got. Charred seeds include wheat, barley and pea from the west, and broomcorn millet and foxtail millet from the east. In combination with previous published dates, we set up routes of crop dispersal and brief history of human activities on the central TP. Neolithic people had occupied the Yarlung Tsangpo Valley from the different direction of the TP in the third millennium BC with different western crops or eastern crops, and moved along the River and its tributaries. The route for dispersal is similar with the historic highland silk road, indicating this road had played a important role since prehistory.