Emperor Taizong's Campaign Against Xiyu States - Campaign Against Gaochang

Campaign Against Gaochang

Meanwhile, Gaochang remained hostile to both Yanqi and Tang, and also in 638, Gaochang, allied with the Chuyue (處月) and Chumi (處密) tribes, attacked Yanqi, capturing five Yanqi cities and 1,500 Yanqi men and women before retreating. Qu Wentai also entered into an alliance with Ashina Bobu against a Tang ally, Yiwu (伊吾), in modern Hami Prefecture, Xinjiang), as well as Yanqi. In 639, Emperor Taizong issued an edict rebuking Qu Wentai and ordering him to send his official Ashian Ju (阿史那矩) to Tang in order to discuss Tang-Gaochang relations; Qu Wentai refused to send Ashina Ju, but instead sent another official, Qu Yong (麴雍), to apologize. Emperor Taizong also ordered Qu Wentai to turn over the Chinese who were previously in exile in the Eastern Turkic Khaganate who had fled to Gaochang when Tang conquered the Eastern Turkic Khaganate in 630. Qu Wentai further incensed Emperor Taizong by trying to persuade Xueyantuo's Zhenzhu Khan Yi'nan to take a more independent stance from Tang. Emperor Taizong began planning an invasion against Gaochang, and Yi'nan offered to assist, although historical records did not indicate any actual Xueyantuo participation.

Around the new year 640, after Emperor Taizong's last attempt to get Qu Wentai to change his anti-Tang stance failed, Emperor Taizong commissioned the general Hou Junji to command an army, assisted by the general Xue Wanjun (薛萬均), to attack Gaochang. Qu Wentai initially did not take the threat seriously—believing that his kingdom was able to withstand an attack from a small Tang army and that Tang could not launch a large army due to logistics issues of marching through the desert. However, by fall 640, Hou had gotten his army through the desert, almost at Gaochang, and Qu Wentai, hearing this, died in anxiety, and was succeeded by his son Qu Zhisheng (麴智盛). Hou, rejecting a proposal to make a surprise attack against Qu Wentai's funeral procession, first attacked and captured Tiandi (田地), just east of Gaochang's capital. He then marched on Gaochang itself. Qu Zhisheng wrote him to apologize for his father's offenses, and Hou ordered him to surrender, which Qu Zhisheng refused. Hou put the city under siege, but Ashina Bobu, instead of aiding Gaochang as he promised, withdrew far from Gaochang, while a general that he had sent to defend Kehanfutu (可汗浮圖, in modern Changji Hui Autonomous Prefecture, Xinjiang), in fear, surrendered to Hou. With no Western Turkic aid coming, Qu Zhisheng surrendered. Emperor Taizong's chancellor Wei Zheng advised allowing Gaochang to remain as a vassal, with Qu Zhisheng continuing to serve as king, but Emperor Taizong decided against doing so, instead annexing Gaochang territory and creating two prefectures—Xi Prefecture (西州, headquartered at Gaochang) and Ting Prefecture (庭州, headquartered at Kehanfutu). He furthered established the Protectorate General to Pacify the West at the fortress of Jiaohe (交河, near Gaochang as well) to keep a military presence. Hou took Qu Zhisheng and his officials back to Chang'an, while returning several cities that Gaochang had previously seized from Yanqi back to Yanqi. Emperor Taizong created Qu Zhisheng the Duke of Jincheng and kept him as a general at Chang'an. Emperor Taizong tried to strengthen Xi Prefecture's defense by commuting the condemned prisoners' death penalties and instead exiling them to Xi Prefecture, while conscripting people originally sentenced to exile into the army defending Xi Prefecture, with a term of service commensurate with the length of exile they were originally sentenced.