Möngke Khan , born Möngke ( / Mönkh / ) (January 11, 1209 – August 11, 1259 ), was the fourth Great Khan of the Mongol Empire, ruling from July 1, 1251, to August 11, 1259. He was the first Great Khan from the Toluid line and made significant reforms to improve the administration of the Empire during his reign. Under Möngke, the Mongols conquered Iraq and Syria as well as the kingdom of Nanzhao.