During the middle to late 7th century, Muslim traders had traversed from the Caliphate to Tang China and established contact with Silla, one of the Three Kingdoms of Korea. In 751, a Chinese general of Goguryeo descent, Gao Xianzhi, led the Battle of Talas for the Tang dynasty against the Abbasid Caliphate but was defeated. The earliest reference to Korea in a non-East Asian geographical work appears in the "General Survey of Roads and Kingdoms" by Istakhri in the mid-9th century.