The Arab army, under the governor of Khurasan Ashras ibn Abdallah al-Sulami, campaigned across the Oxus River to suppress a large-scale rebellion of the subject Soghdian princes that had broken out the previous year and received Türgesh support.

[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.

Soon, however, this policy was reversed—possibly due to pressure from the Caliph himself—and the often brutal measures the Arab tax-gatherers employed to gather the taxes from the mawali and the local landed aristocracy (dihqans) led to a general revolt in Transoxiana.

A vanguard under Qatan, son of Qutayba ibn Muslim, was sent over the river and established a fortified camp, but with the arrival of the combined native Soghdian and Türgesh armies, the bulk of the Arab force was unable to cross for three months.

At this point, according to the account preserved by al-Tabari, the Tamimi warrior al-Harith ibn Surayj, who was later to lead a widespread revolt in Khurasan, urged the Arabs forward, crying that "being killed by the sword is nobler in (this) world and greater in reward with God than death by thirst".

[15] Encouraged by his example, the Tamimi and Qaysi cavalry under al-Harith and Qatan broke through the Türgesh lines and reached the water sources, narrowly staving off a second "Day of Thirst" and allowing Ashras to continue his advance towards Bukhara.

In early 730, Ashras' newly appointed successor Junayd ibn Abd al-Rahman al-Murri tried to reach the army, which was still encamped in the Bukhara oasis, he had to be escorted from Amul by 7,000 cavalry who were attacked on the way by the Türgesh and almost destroyed.