The Battle of Talas was a military encounter and engagement between the Islamic civilization and the Chinese civilization in the 8th century, specifically between Abbasid Caliphate along with its ally, the Tibetan Empire, against the Chinese Tang dynasty. In July 751 AD, Tang and Abbasid forces met in the valley of the Talas River to vie for control over the Syr Darya region of central Asia. According to Chinese sources, after several days of stalemate, the Karluk Turks, originally allied to the Tang Dynasty, defected to the Abbasid army and tipped the balance of power, resulting in a Tang rout. The defeat marked the end of the Tang westward expansion and resulted in Muslims control of Transoxiana for the next 400 years. Control of the region was economically beneficial for the Abbasids because it was on the Silk Road. Chinese prisoners captured in the aftermath of the battle are said to have brought paper-making technology to West Asia.