The region of Transoxiana (Arabic: "Ma wara' al-nahr") had been conquered by the Muslim Arabs of the Umayyad Caliphate under Qutayba ibn Muslim in 705–715, following the Muslim conquest of Persia and of Khurasan in the mid-7th century. The loyalty of Transoxiana's native Iranian and Turkic populations to the Umayyads remained questionable, however, and in 719 the various Transoxianian princes sent a petition to the Chinese court and their Türgesh vassals for military aid against the Caliphate's governors. In response, from the Türgesh launched a series of attacks against the Umayyads in Transoxiana, coupled with uprisings among the native Sogdians. The Umayyad governors initially managed to suppress the unrest, but control over the Ferghana Valley was lost and in 724 the Arabs suffered a major disaster (the "Day of Thirst") while trying to recapture it. The Umayyad government made some half-hearted attempts to placate the local population and win the support of local elites, but in 728 a large-scale uprising broke out. With Türgesh aid, the Umayyad garrisons were evicted, and the Caliphate lost most of Transoxiana except for the region around Samarkand.