Berke Khan (died 1266) (also Birkai; Mongolian: Бэрх хаан, Tatar: Бәркә хан) was a grandson of Genghis Khan and a Mongolian military commander and ruler of the Golden Horde (division of the Mongol Empire) who effectively consolidated the power of the Blue Horde and White Horde from 1257 to 1266. He succeeded his brother Batu Khan of the Blue Horde (West) and was responsible for the first official establishment of Islam in a khanate of the Mongol Empire. He allied with the Egyptian Mamluks against another Mongol khanate based in Persia, the Ilkhanate. Berke also supported Ariq Böke against Kublai in the Toluid Civil War, but did not intervene militarily in the war because he was occupied in his own war against his cousin, Hulagu Khan.