6世纪中叶兴起于漠北的突厥民族,稍后因内部矛盾分为两部。其中,东突厥汗国在广袤的蒙古草原上称霸,成为鲜卑、柔然之后严重威胁中原王朝的草原势力。虽然隋朝数次用兵征讨,使之归附,但东突厥趁着隋末唐初改朝换代的全国混战之机,重新强盛。唐武德九年(626),东突厥颉利可汗亲自率领十万大军抵达渭水便桥,大有直取长安之势,刚即位的唐太宗被迫签订城下之盟。太宗经过几年的 The Turks, which originated in Mobei in the mid-sixth century, were divided into two by internal contradictions. Among them, the Eastern Turkestan Khanate dominated the vast Mongolian grasslands, become Xianbei, Rouran later seriously threatened the Central Plains dynasty of the prairie forces. Although the Sui Dynasty consulted for several times to make it belong to the annexation, the East Turkestan took advantage of the opportunity of the nationwide melee in the late Sui and Tang Dynasties to regain power and prospered again. Tang Takenori nine years (626), the East Turkestan Jie Lik Khan personally led thousands of troops arrived in Wei Shuo Bridge, there is a straightforward Changan trend, just as Emperor Taizong was forced to sign the League under the city. Taizong after several years