The Mongol campaign against the Nizaris of the Alamut period (the Assassins) began in 1253 after the Mongol conquest of the Khwarazmian Empire of Iran by the Mongol Empire and a series of Nizari–Mongol conflicts. The campaign was ordered by the Great Khan Möngke and was led by his brother, Hülegü. The campaign against the Nizaris and later the Abbasid Caliphate was intended to establish a new khanate in the region—the Ilkhanate.