Nizari Ismaili state in the context of "Sack of Baghdad"

The Mongol conquest of Persia and Mesopotamia comprised three Mongol campaigns against Islamic states in the Middle East and Central Asia between 1219 and 1258. These campaigns led to the termination of the Khwarazmian Empire, the Nizari Ismaili state, and the Abbasid Caliphate of Baghdad, and the establishment of the Mongol Ilkhanate government in their place in Persia.

Genghis Khan had unified the Mongolic peoples and conquered the Western Xia state in the late 12th and early 13th centuries. After a series of diplomatic provocations on the part of Muhammad II, the ruler of the neighbouring Khwarazmian Empire, the Mongols launched an invasion in 1219. The invaders laid waste to the Transoxianan cities of Bukhara, Samarkand, and Gurganj in turn, before obliterating the region of Khorasan, slaughtering the inhabitants of Herat, Nishapur, and Merv, three of the largest cities in the world. Muhammad died destitute on an island in the Caspian Sea. His son and successor, Jalal al-Din, tried to resist the Mongols, but was defeated and forced into exile. Genghis returned to his campaign against the Jin dynasty in 1223, only retaining governance of the northern Khwarazmian regions.

The siege of Baghdad took place in early 1258. A large army commanded by Hulegu, a prince of the Mongol Empire, attacked the historic capital of the Abbasid Caliphate after a series of provocations from its ruler, caliph al-Musta'sim. Within a few weeks, Baghdad fell and was sacked by the Mongol army—al-Musta'sim was killed alongside hundreds of thousands of his subjects. The city's fall has traditionally been seen as marking the end of the Islamic Golden Age; in reality, its ramifications are uncertain.

After the accession of his brother Möngke Khan to the Mongol throne in 1251, Hulegu, a grandson of Genghis Khan, was dispatched westwards to Persia to secure the region. His massive army of over 138,000 men took years to reach the region but then quickly attacked and overpowered the Nizari Ismaili Assassins in 1256. The Mongols had expected al-Musta'sim to provide reinforcements for their army—the Caliph's failure to do so, combined with his arrogance in negotiations, convinced Hulegu to overthrow him in late 1257. Invading Mesopotamia from all sides, the Mongol army soon approached Baghdad, routing a sortie on 17 January 1258 by flooding their opponents' camp. They then invested Baghdad, which was left with around 30,000 troops.

The various states and civilizations in Iran (Persia) have had numerous capital cities and royal centers throughout history.

• Ahar; Pishkinid dynasty
• Anshan; pre-Achaemenid era
• Ardabil; early Safavid era, Sajid
• Asaak; Parthian era royal center
• Astara; Ispahbads of Gilan
• Alamut Castle; Nizari Ismaili state
• Amol; Ziyarid, Alavid, Marashis, Dabuyid, Bavandid, Chalavi, (Parthian Empire climate capital)
• Babylon; Achaemenid era
• Baghdad; caliphates, Jalayerid, Buyid
• Balkh; in legend, the governmental center of the Kayanian dynasty
• Bardsir; Banu Ilyas
• Basra; Jalayerid
• Bukhara; Samanid era
• Ctesiphon; Parthian, Sasanian era
• Damavand; Masmughans of Damavand
• Dinavar; Hasanwayhids
• Diyarbakır; Aq Qoyunlu
• Fuman; Dabuyid
• Farim (Perim); Bavandid
• Firozkoh; Ghurid
• Firuzkuh; Chalavi
• Shahr-e Qumis (Hecatompylos); Parthian era
• Ghazna; Ghurid, Khwarazmid, Ghaznavid
• Gor (Firuzabad); Sasanian era
• Gorgan (Astarabad); Ziyarid, Alavids
• Herat; Ghurid, Kartids, Timurid Empire
• Hulwan; Annazids
• Ij (Ig); Shabankara
• Isfahan; Ziyarid dynasty, Kakuyid Emirate, Injuid dynasty, Seljuk era, Safavid era
• Istakhr; Sasanian era
• Izeh (Idaj); Hazaraspids
• Ecbatana (later Hamadan); Median Empire, Achaemenid era, Eldiguzids, Seljuks (Greater and Iraq Seljuks)
• Kerman; Muzaffarid, Qutlugh-Khanids
• Khorramabad; Khorshidi dynasty
• Kunya Urgench; early Khwarezmid era
• Lafur; Qarinvand dynasty
• Lankaran; Talysh Khanate
• Lahijan; Karkiya dynasty
• Maragheh; Ilkhanid, Ahmadilis, Sajid
• Mashhad; Afsharid
• Merv; capital during al-Mamun's caliphate, and Taherid era, Seljuk Empire
• Mosul; winter capital during Qara Qoyunlu
• Nakhchivan; Eldiguzids
• Nishapur; Ilkhanid, Seljuq, Taherid eras
• Nisa, Turkmenistan; periodical capital of the Parthian era
• Pasargadae; Achaemenid
• Persepolis; Achaemenid ceremonial capital
• Rey (Rhagae); Median, Ziyarid, Buyid, Seljuk Empire
• Rudbar; Justanids
• Qazvin; early Safavid era
• Sabzevar; Sarbadars
• Samarkand; Samanid, Khwarazmid, Timurid era
• Shiraz; Buyid dynasty, Injuid dynasty, Muzaffarid dynasty, Salghurid dynasty, Zand dynasty
• Soltaniyeh; Ilkhanid
• Susa; Achaemenid, Parthian era
• Tabriz; Ilkhanid, Khwarezmid, Rawadid, Chupanid, Jalayerid, Eldiguzids, Kara Koyunlu, Aq Qoyunlu, early Safavid era
• Tarom; Sallarid
• Sari; Qajar, Dabuyid, Alavid, Bavandid, Marashis
• Yazd; Kakuyid, Atabegs of Yazd
• Zaranj; Saffarid Empire, Mihrabanid, Nasrid
• Tehran; Qajar era, Pahlavi era, Islamic Republic of Iran 1796–present

The Ziyarid dynasty (Persian: زیاریان) was an Iranian dynasty of Gilaki origin that ruled Tabaristan from 931 to 1090 during the Iranian Intermezzo period. The empire rose to prominence during the leadership of Mardavij. After his death, his brother Vushmgir and his Samanid allies led the dynasty in wrestling for control over territory against the Buyids in the early- to mid-10th century. When Vushmgir died, his sons Bisutun and Qabus fought for influence. Qabus would eventually outlive his brother and ruled the kingdom. However, Qabus was placed in exile from 980 to 998 by the Buyid ruler, Adud al-Dawla who would then dominate Tabaristan, the heartland of Ziyarid power. A succession of other rulers came to rule the kingdom with Ghaznavid support in the early 11th century. The Nizari Ismaili state invaded and ended Ziyarid rule in 1090.

At its greatest extent, it ruled much of present-day western and northern Iran. During the turn of the century, the kingdom attracted many scholars, with the most notable being al-Biruni.

The Mongol campaign against the Nizaris of the Alamut period (the Nizari Ismaili state) began in 1253 after the Mongol invasion of 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 fighting 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.

Alamut (Persian: الموت, meaning "eagle's nest") is a ruined mountain fortress located in the Alamut region in the South Caspian, near the village of Gazor Khan in Qazvin Province in Iran, approximately 200 km (130 mi) from present-day Tehran.

In 1090 AD, the Alamut Castle, a mountain fortress in present-day Iran, came into the possession of Hassan-i Sabbah, a champion of the Nizari Ismaili cause. Until 1256, Alamut functioned as the headquarters of the Nizari Ismaili state, which included a series of strategic strongholds scattered throughout Persia and Syria, with each stronghold being surrounded by swathes of hostile territory.