Mongols launched a campaign against the Nizari Ismaili state in 1253 after the invading the Khwarazmian 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.
Hülegü's campaign began with attacks on strongholds in Quhistan and Qumis amidst intensified internal dissensions among Nizari leaders under Imam Muhammad III of Alamut whose policy was to fight against the Mongols. His successor, Rukn al-Din Khurshah, began a long series of negotiations in face of the implacable Mongol advance. In 1256, the Imam capitulated while besieged in Maymun-Diz and ordered his followers to do likewise according to his agreement with Hülegü. Despite being difficult to capture, Alamut ceased hostilities too and was dismantled. The Nizari state was thus disestablished, although several individual forts, notably Lambsar, Gerdkuh, and those in Syria continued to resist. Möngke Khan later ordered a general massacre of all Nizaris, including Khurshah and his family.
Many of the surviving Nizaris were absorbed into the Ismaili communities in Western, Central, and South Asia, or assimilated into local Sunni population while practicing taqiyya. Little is known about them afterward, but their communities regain some sort of independence in their heartland of Daylam and their Imamate reappeared later in Anjudan.
Sources The main primary source is the Tarikh-i Jahangushay written by the historian Ata-Malik Juvayni, who was present in the campaign as an official under Hulegu. Juvayni has dedicated the concluding one-third of his history to this campaign, depicting it as the pinnacle of the Mongol conquest in the Muslim lands. His account contains inconsistencies and exaggerations and has been "corrected" based on other sources. Other sources include the Jami' al-Tawarikh written by Rashid al-Din Hamadani and the Tarikh-i Tabaristan by Ibn Isfandiyar.
Background
The Nizaris were a branch of Ismailis, itself a branch of Shia Muslims. By establishing strategic and self-sufficient mountain strongholds, they had established a state of their own within the territories of the Seljuq and later Khwarezmian empires of Persia.
In 1192 or 1193, Rashid al-Din Sinan had been succeeded by the Persian da'i Nasr al-Ajami, who restored Alamut suzerainty over the Nizaris in Syria. After the Mongol invasion of Persia, many Sunni and Shia Muslims (including the prominent scholar al-Tusi) had taken refuge with the Nizaris of Quhistan. The governor (muhtasham) of Quhistan was Nasir al-Din Abu al-Fath Abd al-Rahim ibn Abi Mansur.
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 confrontations 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:B. Hourcade, “Alamüt,” Encyclopædia Iranica, I/8, pp. 797–801; an updated version is available online at http://www.iranicaonline.org/articles/alamut-valley-alborz-northeast-of-qazvin- (accessed on 17 May 2014). 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 the Nizari muhtashams (governors) 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 them, 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 the 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.
Hülegü's campaign
Campaign against Quhistan, Qumis, and Khurasan
In March 1253, Hülegü's advance guard under the command of Kitbuqa crossed the Oxus (Amu Darya) with 12,000 men (one tümen plus two mingghans under Köke Ilgei). In April 1253, they captured several Nizari fortresses in Quhistan and killed their inhabitants, and in May they attacked the district of Qumis and laid siege to Gerdkuh, the main Nizari stronghold there. His army consisted of 5,000 (probably Mongol) cavalrymen and 5,000 (probably Tajik) infantrymen. Kitbuqa left an army under amir Büri to besiege Gerdkuh, and himself attacked the nearby Mihrin (Mehrnegar) castle and Shah (in Qasran?). In August 1253, he sent raiding parties to the Tarem and Rudbar districts with little results. Afterward they attacked and slaughtered the inhabitants of Mansuriah and Alabeshin (Alah beshin).
In October 1253, Hülegü left his orda in Mongolia and began his march with a tümen at a leisurely pace and increased his number in his way. He was accompanied by two of his ten sons, Abaqa and Yoshmut, his brother Subedei, who died en route, his wives Öljei and Yisut, and his stepmother Doquz.
In July 1253, Kitbuqa who had been in Quhistan, pillaged, slaughtered, and seized probably temporarily Tun (Ferdows) and Turshiz. A few months later, Mehrin and several other castles in Qumis fell as well. In December 1253, Girdkuh's garrison audaciously sallied at night and killed a hundred Mongols, including Büri. Gerdkuh was on the verge of falling due to an outbreak of cholera, but unlike Lambsar, it survived the epidemic and was saved by the arrival of reinforcements from Alamut sent by the Imam Ala al-Din Muhammad in the summer of 1254. The impregnable fort resisted for many years (see below).
In September 1255, Hülegü arrived near Samarqand. He then made Kish (Shahrisabz) his temporary headquarters, and sent messengers to the local Mongol and non-Mongol rulers in Persia, announcing his presence as the Great Khan's viceroy and asking for assistance against the Nizaris, with the punishment of refusal being their utter destruction. In Autumn 1255, Arghun Aqa joined him. All of the rulers of Rum (Anatolia), Fars, Iraq, Azerbaijan, Arran, Shirvan, Georgia, and supposedly also Armenia, acknowledged their service with many gifts.
The inexorable Mongol advances in Quhistan caused consternation among the Nizari leadership. The relationship had already deteriorated between Imam Ala al-Din Muhammad, who was reportedly afflicted by melancholia, and his advisors and Nizari leaders, as well as with his son Rukn al-Din Khurshah, the designated future Imam. According to Persian historians, the Nizari elites had planned a "coup" against Muhammad in order to replace him with Khurshah who would subsequently enter into immediate negotiations with the Mongols, but Khurshah fell ill before implementing this plan. Nevertheless, on December 1 or 2, 1255, Muhammad died under suspicious circumstances and was succeeded by Khurshah who was in his late twenties.
To reach Iran, Hülegü had entered via the Chaghatai khaganate, crossing the Oxus (Amu Darya) in January 1256, spent the winter in the meadows of Shafurqan near Balkh, and entered Quhistan in April 1256. Hülegü chose Tun, which had not been reduced effectively by Kitbuqa, as his first target. An obscure incident occurred while Hülegü was passing through the Zawa and Khwaf districts which deterred him from supervising the campaign. He instructed Kitbuqa and Köke Ilgei in May 1256 to attack Tun again, which was sacked after a week-long siege, and almost all its inhabitants were massacred. The Mongol commanders then regrouped with Hülegü and attacked Tus. Probably at this point, Hülegü received Nasir al-Din, the patron of the scholar Nasir al-Din al-Tusi and the last muhtasham in Quhistan. When asked by Hülegü why he did not bring his garrison, the muhtasham explained that the Nizaris obey only their Imam, Khurshah.The muhtasham Nāṣir al-Dīn had been previously persuaded by Malik Shams al-Din Muhammad of Herat. The Kartid ruler of Herat had been sent on a mission on Hülegü's behalf while the muhtasham was residing in the fortress of Sartahkt. After his capitulation, Hülegü gave the aged muhtasham a yarligh and a paiza, and appointed him as the ruler of the ruined city of Tun. He died around a year later in Safar 655 AH (February/March 1257).
Campaign against Rudbar and Alamut
As soon as he had been in power, Khurshah announced the Nizari leadership's willingness to submit to the Mongol rule to the nearest Mongol commander, noyan Yasur (or Yasa'ur) in Qazvin. Yasur replied that the Imam personally should visit Hülegü's camp. Skrimishes are recorded between Yasur and the Nizaris of Rudbar: on June 12, he was defeated in a battle on Mount Siyalan near Alamut, where the Nizari forces had been mustered, but managed to harass the Nizaris of the region.Jami' al-Tawarikh
As Hülegü reached Bistam, his army had enlarged into five tümens, and new commanders were added. Many of them were the relatives of Batu Khan. From the ulus of Jochi representing the Golden Horde came Quli (son of Orda), Balagha, and Tutar. The Chagatai Khanate forces were under Tegüder. A contingent of Oirat tribesmen also joined under Buqa Temür. No member of Ögedei's family is mentioned. Hülegü had with him a thousand squads of siege engineers (probably north Chinese, Khitan and Muslim) skilled in the use of mangonels and naphtha.