Yunnan-Tibet! The Ancient Tea Horse Caravan Road
... This route would appear to have been in use long before it became an avenue for the tea and horse trade during the Tang and the Song dynasties, for it was a very important corridor connecting the ancient cultures of the areas of present Tibet, Yunnan and Sichuan.
In such places as Ganzi and Aba districts of Sichuan and the Hengduan Mountains of Northwest Yunnan archaeologists have discovered many cist tombs which date from the Shang (ca. 1600-ca.1100 BCE) and the Zhou (ca. 1100-256 BCE) dynasties. These cist tombs are scattered broadly in the canyons and valleys of the upper reaches of the Min River as well as the Yalong and Jinsha Rivers. Most of these tombs are located in western Sichuan and western Yunnan, although a few have also been found in Tibet.