Excerpts from Books and Wikipedia
The battlefield is located in modern Kyrgyzstan. Later the Arabs captured Bokhara and Samarkand on the Silk Road. [Furtado: 1001 Days] "The defeat marked the end of the Tang westward expansion and resulted in Muslim Arab 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." [Wikipedia] "The incident that led directly to the Battle of the Talas River concerned some petty central Asian kingdoms. The rulers of Ferghana and Tashkent were feuding, and the king of Ferghana sought assistance from the local Chinese official, Gao Hsien-chih. Tashkent, in turn, sought aid from the Abbasids, and both the Chinese and the Abbasids responded by dispatching armies." [Aldrete: Decisive Battles]