Qilian Mountains
The Wusun were first mentioned by Chinese sources as living together with the Yuezhi between the Qilian Mountains and Dunhuang (Gansu), although different locations have been suggested for these toponyms. Beckwith suggests that the Wusun were an eastern remnant of the Indo-Aryans, who had been suddenly pushed to the extremities of the Eurasian Steppe by the Iranian peoples in the 2nd millennium BCE.