The Liao Dynasty, also known as the Khitan Empire, was a state that ruled over the regions of Manchuria, Mongolia, and parts of northern China proper. It was founded by the Yel? clan of the Khitan people in the same year as the Tang Dynasty collapsed (907), even though its first ruler, Yel? Abaoji (Yaruud Ambagai Khan), did not declare an era name until 916. Although it was originally known as the Empire of the Khitan, the Emperor Yel? Ruan officially adopted the name 'Liao' (formally ˉGreat Liaoˇ) in 947. Another name for China in English, Cathay, is derived from the name Khitan. This is also the origin of the Russian word for China, ????? or Kitay, and that of several other East European languages. The Liao Empire was destroyed by the Jurchen of the Jin Dynasty in 1125. However, remnants of its people led by Yel? Dashi established the Xi (Western) Liao Dynasty 1125-1220, also known as Kara-Khitan Khanate, which extended its influence over Central Asia into Persia and survived until the arrival of Genghis Khan's unified Mongolian army.