 Protected by the Taklamakan Desert from steppe nomads, elements of Tocharian culture survived until the 7th century, when Turkic immigrants from the collapsing Uyghur Khaganate of modern-day Mongolia began to absorb the Tocharians to form the modern-day Uyghur ethnic group.In 744 the Uyghur Khaganate (744–840) was formed as a confederation of nine Uyghur clans.The Tang allied with the Uyghur Bayanchur Khan to suppress the An Lushan rebellion, An Lushan himself being from Soghdian-Turkish descend.