The region of Transoxiana had been conquered by the Umayyad leader Qutayba ibn Muslim in the reign of al-Walid I (r. 705–715), following the Muslim conquests of Persia and Khurasan in the mid-7th century.[1][2] The loyalties of Transoxiana's native Iranian and Turkic populations and of the autonomous local rulers remained questionable, however: in 719 the Transoxianian princes sent a petition to the Chinese court and their Türgesh vassals for military aid against the Umayyad Caliphate's governors.[3] In response, from 720 on the Türgesh launched a series of attacks against the Muslims in Transoxiana, coupled with uprisings against the Caliphate among the local Sogdians.