Ariq Boke or Arigh Bukha, the youngest son of Tolui, was a grandson of Genghis Khan and a claimant to the Mongol Empire. His brothers were Möngke Khan, Hulagu Khan and Kublai Khan. In 1259 the Great Khan Möngke died. As Ariq Boke was commander of the Mongol homelands, and as Kublai Khan was campaigning against Song China at the time of Möngke's death, he decided to attempt to make himself Khan. Wikipedia
The definitive Wikipedia entry for Ariq Boke. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Ariq_Boke