Mongol campaign against the Nizaris participant Nizari Ismaili state
Early Nizari–Mongol relations
In 1221, the Nizari Imam Jalal al-Din Hasan sent emissaries to Genghis Khan in Balkh. The Imam died in the same year and was succeeded by his 9-years-old son, Ala al-Din Muhammad.
After the fall of the Khwarezmian dynasty as a result of the Mongol invasion, direct confrontation began between the Nizaris under Imam Ala al-Din Muhammad and the Mongols under Ögedei Khan. The latter had just begun to conquer the rest of Persia. Soon the Nizaris lost Damghan in Qumis to the Mongols; the Nizaris had recently taken control of the city after the fall of the Khwarezmshahs.The Nizari Imam sought anti-Mongol alliances as far as China, France, and England: in 1238, he and the Abbasid caliph Al-Mustansir sent a joint diplomatic mission to the European kings Louis IX of France and Edward I of England to forge a Muslim–Christian alliance against the Mongols, but this was unsuccessful. The European kings later joined the Mongols against the Muslims.In 1246, the Nizari Imam, together with the new Abbasid caliph Al-Musta'sim and many Muslim rulers, sent a diplomatic mission under Nizari muhtashams (governor) of Quhistan Shihab al-Din and Shams al-Din to Mongolia on the occasion of the enthronement of the new Mongol Great Khan, Güyük Khan; but the latter dismissed it, and soon dispatched reinforcements under Eljigidei to Persia, instructing him to dedicate one-fifth of the forces there to reduce rebellious territories, beginning with the Nizari state. Güyük himself had intended to participate but died shortly afterward. A Mongol noyan (commander), Chagatai the Elder, was reportedly assassinated by the Nizaris around this time.Güyük's successor, Möngke Khan, began to implement the former's schemes. Möngke's decision followed anti-Nizari urges by Sunnis in the Mongol court, new anti-Nizari complaints (such as that of Shams al-Din, qadi of Qazvin), and warnings from local Mongol commanders in Persia. In 1252, Möngke entrusted the mission of conquering the rest of Western Asia to his brother Hülegü, with the highest priority being the conquest of the Nizari state and the Abbasid Caliphate. Elaborate preparations were made, and Hülegü did not set out until 1253, and actually arrived in Persia more than two years later.  In 1253, William of Rubruck, a Flemish priest sent on a mission to Karakorum in Mongolia, was struck by the security precautions there, reportedly in response to the more than forty assassins who had been sent there to assassinate Möngke; it is possible that the assassination attempt was merely rumored.