 In 730 a peace treaty with China was signed which established the border east of Kokonor at the Chiling Pass in the Red Hills.In 733 Mes-ag-tshoms wrote to the Chinese emperor Xuanzong (r. 712-756) stating that China and Tibet were equally great kingdoms and hoping that peace would endure.In 734 a pillar engraved with the treaty was erected, and although it was apparently torn down soon after, envoys travelled regularly between the Lhasa and Chang'an for the next fifteen years.