The military of the Tang Dynasty was staffed with a large population of Turkic soldiers, referred to as Tujue in Chinese sources. Tang elites in northern China were familiar with Turkic culture, a factor that contributed to the Tang acceptance of Turkic recruits. The Tang emperor Taizong adopted the title of "Heavenly Kaghan" and promoted a cosmopolitan empire. Taizong regularly recruited and promoted military officers of Turkic ancestry, whose steppe experience contributed to the western and northern expansion of the Tang empire. The Turkic general Ashina She'er participated in the Tang capture of the Karakhoja, Karasahr, and Kucha kingdoms in Xinjiang. The half-Turkic general An Lushan started a revolt that led to the decline of Tang Dynasty.