Which Mongol ruler sacked Baghdad in 1258?

Hulagu Khan sacked Baghdad in 1258. A grandson of Genghis Khan, Hulagu led the Mongol campaign into Persia and Mesopotamia on the orders of his brother, Möngke Khan.

The siege began in January 1258 after the Abbasid caliph al-Musta'sim refused to submit. Mongol forces breached the city’s defenses, and Baghdad surrendered on 10 February. The sack began soon afterward. The Abbasid Caliphate, which had ruled from Baghdad since 750, effectively ended when the caliph was captured and killed.

The event is traditionally associated with the end of the Islamic Golden Age, although historians caution that intellectual and scientific activity continued elsewhere and that the idea of a single abrupt ending is too simple. Hulagu later established the Ilkhanate in Persia. He is also frequently spelled Hulegu or Hülegü, so those spellings refer to the same ruler rather than different khans.