In 1618, the Torghut and a small contingent of Dörbet Oirats (200,000-250,000 people) chose to migrate from the upper Irtysh River region to the grazing pastures of the lower Volga region south of Saratov and north of the Caspian Sea on both banks of the Volga River. The Torghut were led by their taishi, Kho Orluk. They were the largest Oirat tribe to migrate, bringing along nearly the entire tribe. The second-largest group was the Dörbet Oirats under their taishi, Dalai Batur. Together they moved west through southern Siberia and the southern Ural Mountains, avoiding the more direct route that would have taken them through the heart of the territory of their enemy, the Kazakhs. En route, they raided Russian settlements and Kazakh and Bashkir encampments.