of Chaghaniyan; his second campaign, in 740, recovered much territory in Sogdia, including Samarkand, with little apparent resistance. Aiming to recover all the lands previously held under Qutayba ibn Muslim and to curtail the activities of the renegade Ibn Surayj, who was based there, Nasr then launched an expedition targeting al-Shash (Tashkent). The principality of Usrushana submitted peacefully, but when the Muslim army reached the Jaxartes, it was confronted by a 15,000-strong force from Shash along with Ibn Surayj's men and some Türgesh; according to Arab tradition, the latter were led by Suluk's murderer and successor, Kursul. According to the Arab sources, Nasr was able to drive off the Türgesh and scored a victory against one of their detachments, killing its chief. He apparently failed to subdue al-Shash, for he was forced to content himself with an agreement with the ruler of Shash, whereby Ibn Surayj was evicted to Farab, where the latter was left unmolested to continue his opposition to the Umayyads. Nasr also launched two expeditions against Ferghana, which plundered and ravaged the countryside and took many captives. It seems, however, that the Muslim reconquest at this time did not extend much further than Samarkand, with occasional tribute being possibly levied from the remoter principalities. Outwardly at least, by 743 the Umayyad position in Khurasan appeared stronger than ever. The reality beneath the splendid façade however was different. Tension and mutual mistrust existed between the Khurasani Arab levies () and the 20,000 Syrian troops introduced into the province as a security measure after the disastrous Battle of the Defile in 731, while tribal antagonisms continued to create trouble: apart from continued Yemeni resentment at Nasr, there was strong dislike of the Umayyads' Syrian regime, fanned by their unjust tax policies. Although Nasr tried to remedy the situation, it was too late. In addition, Khurasan was a major center of early Shiism, and specifically of the Kaysanite sect of the , which had gained wide acceptance in the province, especially among the . In 742–743, Nasr confronted and defeated a revolt led by Yahya, son of Zayd ibn Ali and the leader of the in Khurasan. Yahya was captured and executed, and the resulting vacuum in Hashimi leadership opened the path for the Khurasani branch of the movement to come under the control of the Abbasid family. It is however, a testament to the "respect and even affection" (Gibb)