 In 657, Tang Dynasty general Su Dingfang defeated Ashina Helu, qaghan of the Western Turkic Khaganate, at the Battle of Irtysh River, ending the Tang campaign against the Western Turks.Helu's defeat ended the Khaganate, strengthened Tang control of Xinjiang, and led to Tang suzerainty over the western Turks.In the 15th and 16th centuries the lower and middle courses of the Irtysh lay within the Tatar Khanate of Sibir; its capital, Qashliq (also known as Sibir) was located on the Irtysh a few miles upstream from the mouth of the Tobol (where today's Tobolsk is situated).