Hulagu Khan (ca. 1216-1265) was a Mongol conqueror and the founder of the dynasty of the Il-Khans of Iran. He also suppressed the Ismaili sect and defeated the last Abbasid caliph.

Hulagu--the native form of his name is Hüle'ü, whence the Alau of Marco Polo--was a grandson of Genghis Khan and the younger brother of the Great Khans Mangu (Möngkë) and Kublai. At a kuriltai, or assembly of the Mongol princes, held in 1251 at the time of Mangu's accession, it was decided that Hulagu should consolidate the conquests in western Asia by suppressing the sect of the Ismailis, or Assassins of Alamut, in northwestern Persia and then, if necessary, attacking the caliphate.

Hulagu left Mongolia in the autumn of 1253 at the head of a large army. Traveling slowly along a carefully prepared route, from which all natural obstacles had been removed, he...