Möngke’s sudden death from dysentery during the campaign against the Song fortress of Hezhou leads to another succession crisis, as Kublai and his younger brother Ariq Böge, sons of Genghis Khan’s son Tolui, both claim the Mongol throne.

Arigböge, supported by the traditionalists who distrust Kublai’s modernizing bent, summons a kuriltai at Karakorum, about two weeks after a similar event convoked by Kublai at Zhongdu.

Both are elected supreme ruler, or khakhan.

Kublai sends an army toward Karakorum, but Ariq Böge retreats westward with his forces.

The two Mongol armies clash, then withdraw without a decisive settlement.