The Battle of Talas (or Battle of Artlakh; Chinese: 怛羅斯會戰; Arabic: معركة نهر طلاس‎) was a military engagement between the Arab Abbasid Caliphate along with their ally the Tibetan Empire and the Chinese Tang Dynasty, then under Emperor Xuanzong. In July 751 C.E., Tang and Abbasid forces met in the valley of the Talas River to vie for control of the Syr Darya region of central Asia. The battle was a major defeat for the Tang and marked the end of their westward territorial expansion, resulting in Muslim control of Transoxiana for the next four hundred years. Control of this region was economically beneficial for the Abbasids because it was on the Silk Road.