hostilities between the tang and the western turks had existed since the founding of the dynasty. emperor gaozu, the first emperor of the tang dynasty, aided the assassination of a western turk qaghan on november 2, 619. facing the threat of both the western and eastern turkic khaganates, gaozu's successor emperor taizong formed an alliance with the western turks against the eastern turks, adopting a policy of allying "with those who are far away to fight those who are close."