 The nearby kingdom of Karasahr was captured by the Tang in 644 and the kingdom of Kucha was conquered in 649.The expansion into Central Asia continued under Taizong's successor, Emperor Gaozong, who dispatched an army in 657 led by Su Dingfang against the Western Turk qaghan Ashina Helu.Ashina's defeat strengthened Tang rule in southern Xinjiang and brought the regions formerly controlled by the khaganate into the Tang empire.