Muslim conquest of Transoxiana

The Battle of Talas determined the western limit of Tang dynasty expansion into Central Asia. Fighting along the Talas River over control of the regions surrounding the Syr Darya, the Tang army under Gao Xianzhi was defeated by Abbasid forces under Ziyad ibn Salih, with Karluk mercenaries playing a role on the Abbasid side — though sources differ on whether the Karluks fought as standing Abbasid allies or defected from the Tang during the engagement. Tang casualties of 20,000–30,000 against a force of 10,000–20,000 indicate near-total destruction of the Tang contingent. The outcome ended Tang influence in Transoxiana and halted Tang westward expansion into Central Asia, effectively fixing the boundary between Chinese and Islamic spheres of influence in the region. Within the broader Muslim conquest of Transoxiana, the battle confirmed Abbasid dominance over the territory east of the Syr Darya that earlier Arab campaigns had contested across decades of fighting since 673.