Who is considered the last Great Khan of a unified Mongol Empire?

Möngke Khan is generally considered the last Great Khan to rule a still-unified Mongol Empire.

A grandson of Genghis Khan and the eldest son of Tolui, Möngke was elected Great Khan in 1251. He strengthened central administration, ordered financial reforms and censuses, and continued expansion on several fronts. During his reign, Mongol armies campaigned in China, the Middle East, Korea, and other parts of Eurasia.

Möngke’s authority was recognized across the major Mongol uluses, even though the empire was already difficult to govern as a single political system. He died in 1259 during a campaign against the Southern Song in China. His death triggered a succession struggle between his brothers Kublai and Ariq Böke.

Kublai eventually prevailed, but the civil war accelerated the empire’s fragmentation. The Golden Horde, Chagatai Khanate, Ilkhanate, and Yuan realms increasingly acted independently. Kublai Khan was a Great Khan claimant and a powerful ruler, but he is not usually identified as the last Great Khan of a unified empire because unity had broken down during and after the succession conflict.