 After 649, the Tang Dynasty continued their war against the Western Turks under the reign of Emperor Gaozong, Taizong's successor. Gaozong conducted a campaign led by general Su Dingfang against the Western Turk qaghan, Ashina Helu in 657. The qaghan surrendered, the Western Turks were defeated, and the khaganate's former territories were annexed by the Tang. The Tang retreated from beyond the Pamir Mountains in modern Tajikistan and Afghanistan after a Turkic revolt in 662, and lost the Tarim Basin to local revolts and Tibetan incursions in 665-670. The Tang regained the Tarim Basin in 692 and again lost it to the Tibetans in the 790s, the Four Garrisons having already been cut off from the rest of the Tang empire by a Tibetan conquest of the Gansu Corridor. Although the Tibetan empire collapsed in the middle of the ninth century, the Tang Dynasty lacked the means to regain dominance in the Tarim Basin and itself ended in 907 with the abdication of Emperor Ai.
