Chagatai Khanate

The Chagatai Khanate, also known as the Chagatai Ulus, was a Mongol khanate that comprised the lands ruled by Chagatai Khan, second son of Genghis Khan, and his descendants and successors. Over time, its Mongol ruling groups underwent a gradual and uneven process of linguistic and cultural Turkification and Islamization, though Mongolian political and administrative traditions remained important. Mongolian language continued to be used for official documents into the 14th century; Tughlugh Timur and Ilyas Khoja, the first Chaghatayid rulers of Moghulistan, still issued royal edicts in Mongolian. With the division of the Mongol Empire after 1259, it became a functionally separate khanate. At its height in the late 13th century, the khanate extended from the Amu Darya south of the Aral Sea to the Altai Mountains on the border of modern-day Mongolia and China, roughly corresponding to the area once ruled by the Qara Khitai (Western Liao dynasty).