The conquest of the Western Turks, known as the Western Tujue in Chinese sources, is a military campaign in 657 led by the Tang Dynasty general Su Dingfang against the Western Turkic Khaganate ruled by Ashina Helu.

The Chinese war against the Western Turks had begun in 640 with the annexation of the Tarim Basin oasis state Gaochang, an ally of the Western Turks.

Tang expansion into Central Asia had continued with the conquest of Karasahr in 644 and Kucha in 648.

Su Dingfang's army defeats Helu at the battle of Irtysh River.The victory strengthens Tang control of Xinjiang and brings the regions formerly ruled by the Khaganate into the Tang empire.

Puppet qaghans and military garrisons are installed to administer the newly acquired territories.

The Tang Dynasty achieves its maximum extent as China's western borders reach the eastern frontier of the Arabic Umayyad Caliphate.

Later on, Turkic revolts end Chinese hegemony beyond the Pamir Mountains in modern Tajikistan and Afghanistan, but a Tang military presence remains in Dzungaria and the Tarim Basin.

Central Asian culture absorbs artistic and political influences from Tang China, and the Turkic migrants serving under the Tang as soldiers and generals spread Turkic culture and language into Central Asia.