The Battle of Qatwan (Chinese: 卡特萬之戰) was fought in September 1141 between the Qara Khitai (Western Liao dynasty) and the Seljuq Empire and its vassal-state the Kara-Khanid Khanate. The Seljuqs were decisively defeated, which signalled the beginning of the end of the Great Seljuk Empire.