Faced with this crisis, Caliph
Hisham ibn Abd al-Malik () took drastic measures: Khurasan was separated from the purview of the
governor of Iraq and raised to a separate province, under the
Jaziran general Ashras ibn Abdallah al-Sulami. Like his predecessor,
Asad ibn Abdallah al-Qasri, Ashras tried to win over the loyalties of the local population and the native, non-Arab converts to Islam (
mawali) by addressing some of their grievances on taxation. 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. This was made all the more dangerous to the Arabs due to the rebels' call for assistance to the Türgesh ruler, the
khagan, who replied by leading his army in person against the Arabs. By the time the
khagan entered the field in 728, only
Samarkand and the two fortresses of Kamarja and Dabusiyya on the
Zarafshan River remained in Arab hands in all of Transoxiana. In order to confront the Türgesh, Ashras assembled the forces of Khurasan and led them to Amul on the
Oxus River. 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. During this period Qatan's force was beleaguered by the Türgesh, who at the same time crossed the Oxus in small raiding parties. Ashras gave command of his cavalry to Thabit Qutnah, who managed to rout the raiders and drive them to Amul. There the Arabs defeated the Türgesh, although a decisive victory eluded them as Türgesh reinforcements crossed the river and allowed the raiders to escape to safety back over the Oxus. At length Ashras got his forces across, linked up with Qatan ibn Qutayba, and began to advance on
Bukhara. The Arabs beat off attacks to reach the trading town of
Baykand, some five
farsakhs—roughly —south of Bukhara itself and outside the oasis that surrounded the latter. After the Arab army encamped at Baykand, the Türgesh and Soghdians cut off the water supply from the oasis. Threatened with thirst, the Arab army left Baykand and headed for Bukhara, with Qatan in the vanguard. When the Türgesh and Soghdian forces attacked, the vanguard, some 6,000 men, was cut off from the main body under Ashras, and Ashras and Qatan gave each other up for lost until they met again two days later. The king of Samarkand,
Ghurak, who had unto this moment remained ostensibly loyal to the Arabs—although, ever careful to hedge his bets, he had sent his son Mukhtar to the
khagan—now switched sides. Exhausted by thirst, the Arab vanguard was almost cut down by their enemies, losing 700 men. 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". 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. == Aftermath ==