 The Khitan exiles, headed by Yelü Dashi, a member of the Khitan royal family, migrated to the West.The Khitan settled in the Tarbagatai Mountains east of Zhetysu, and their number grew to 40,000 tents.Around 1130 the local Karakhanid ruler of Balasagun asked for their aid against the hostile Kankalis and Karluks.