Göktürks - Eastern Turkic Khaganate

Eastern Turkic Khaganate

The civil war left the empire divided into eastern and western parts. The eastern part, still ruled from Ötüken, remained in the orbit of the Sui Empire and retained the name Göktürk. The qaghans Shibi (609-19) and Illig (620-30) of the East attacked China at its weakest moment during the transition between the Sui and Tang dynasties. On September 11, 615 Shibi Qaghan's army surrounded Emperor Yang of Sui at Yanmen (in present day Dai County, Xinzhou, Shanxi).

In 626, Illig Qaghan took advantage of the Incident at Xuanwu Gate and drove on Chang'an. On September 23, 626 Illig Qaghan and his iron cavalries reached the bank of the Wei River at the north of Bian Bridge (in present day Xianyang, Shaanxi). On September 25, 626 Li Shimin (Emperor Taizong) and Illig Qaghan formed an alliance with slaying a white horse on Bian Bridge. Tang paid compensation and promise further tributes, Illig Qaghan ordered to withdraw their iron cavalries (Alliance of Wei River, 渭水之盟 or Alliance of Bian Qiao 便橋會盟 / 便桥会盟). All in all, 67 incursions on Chinese territories were recorded.

Before mid-October 627 heavy snows on the Mongolian steppe covered the ground to a depth of several feet, preventing the nomads' livestock from grazing and causing a massive dying-off among the animals. According to the New Book of Tang, in 628, Taizong mentioned that "There has been a frost in midsummer. The sun had risen from same place for five days. The moon had had the same light level for three days. The field was filled with red atmosphere (dust storm)."

Illig Qaghan was brought down by a revolt of his Tiele vassal tribes (626-630), allied with Emperor Taizong of Tang. This tribal alliance figures in Chinese records as the Huihe (Uyghur).

On March 27, 630 a Tang army under the command of Li Jing defeated the Eastern Turkic Khaganate under the command of Illig Qaghan at the Battle of Yinshan (陰山之戰 / 阴山之战). Illig Qaghan fled to Ishbara Shad. But on May 2, 630 Zhang Baohiang's army got advance to Ishbara Shad's headquarter. Illig Qaghan was taken prisoner and sent to Chang'an. The Eastern Turkic Khaganate collapsed and was incorporated into the Jimi system of Tang. Emperor Taizong said that "It's enough for me to compensate my dishonor at Wei River."