Around 840 CE a group of Turkic people known as the Uighur were displaced from their ancestral homelands in the Mongolian Steppe, and driven south by Kirghiz raiders. The Uighur moved into the Tarim Basin, settling in the old oasis cities of Kuqa and Aksu before gradually spreading around the rim of the Taklamakan Desert. Here they underwent an extraordinary transformation, changing from pastoral nomads to settled oasis dwellers and cultivators.