the nearby kingdom of karasahr grew wary of the chinese troops stationed at gaochang, now under tang domination. it refused to send tribute to the tang court and formed an alliance with the western turks. a tang campaign led by commander guoxiao ke captured the kingdom in 644 and installed a tang loyalist as ruler. military assistance by the western turks failed to deter the tang forces. with the support of the western turks, the puppet ruler was later deposed, and another military campaign, led by the tang general ashina she'er, a member of the turkic ashina royal family, arrived in 648 to re-establish tang control.