When Möngke died at a siege, two of his brothers were proclaimed Great Khan in the same year and fought for four years

Möngke Khan died in the seventh month of 1259 at Diaoyu Mountain during the siege of a Song fortress near Chongqing, aged 52, without a designated successor. His brothers Kublai and Hülegü were away on campaign. The youngest brother, Ariq Böke, held the capital, Karakorum, with the support of Möngke's family and most of the court^†. Kublai returned north. In the third month of 1260 the princes of the eastern and western wings met him at Kaiping and urged him to take the throne. His accession edict said that among Genghis Khan's grandsons and the late emperor's brothers, "by worth and by age, there is only I". The Yuan History records that in the same season Ariq Böke "usurped the title" west of Karakorum on the Altan River. Kublai blocked grain shipments from north China to Mongolia. His ally Qadan, a son of Ögedei, defeated Ariq Böke's general, and Karakorum changed hands twice^†. After a defeat at Shimultai, Ariq Böke could no longer field an army. In the seventh month of 1264 he came to Kublai with his princes and advisers. Kublai pardoned the princes as descendants of Genghis Khan and executed the advisers. Ariq Böke died a few years later in custody, and rumours said he was poisoned^†. In 1388 his descendant Yesüder took the Mongol throne from Kublai's line^†.