Alamut Castle in the context of "Order of Assassins"

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 Nizari state (the Alamut state) was a Nizari Isma'ili Shia state founded by Hassan-i Sabbah after he took control of the Alamut Castle in 1090 AD, which marked the beginning of an era of Ismailism known as the "Alamut period". Their people were also known as the Assassins or Hashashins.

The state consisted of a nexus of strongholds throughout Persia and the Levant, with their territories being surrounded by huge swathes of hostile as well as crusader territory. It was formed as a result of a religious and political movement of the minority Nizari sect supported by the anti-Seljuk population. Being heavily outnumbered, the Nizaris resisted adversaries by employing strategic, self-sufficient fortresses and the use of unconventional tactics, notably assassination of important adversaries and psychological warfare. They also had a strong sense of community as well as total obedience to their leader.

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.

Hasan-i Sabbah also known as Hasan I of Alamut, was a religious and military leader, founder of the Nizari Ismai'li sect, Order of Assassins, as well as the Nizari Ismaili state, ruling from 1090 to 1124 AD.

Alongside his role as a leader, Sabbah was a scholar of mathematics, most notably in geometry, as well as astronomy and philosophy, especially in epistemology. It is narrated that Hasan and the Persian polymath Omar Khayyam were close friends since their student years. He and each of the later Order of Assassins' leaders came to be known in the West as the Old Man of the Mountain, a name given by Marco Polo that referenced the sect's possession of the commanding mountain fortress of Alamut Castle.

Rukn al-Dīn al-Hasan ibn Muhammad Khurshāh (or Khwarshāh) (ركن الدین الحسن بن محمد خورشاه) (1230–1256) was the son of 'Alā' ad-Dīn Muḥammad III and the 27th Isma'ili Imam. He was also the fifth and final Nizari Isma'ili Imam who ruled at Alamut. The Imam was the eldest son of Imam ʿAla al-Din Muhammad and succeeded his murdered father to the Imamate in 1255. Imam Rukn al-Din engaged in a long series of negotiations with the invading Mongols, and under whose leadership Alamut Castle was surrendered to the Mongol Empire marking the end of the Nizari state in Persia.

Maymūn-Diz (Persian: میمون دز) was a major fortress of the Nizari Ismailis of the Alamut Period described in historical records. It has been variously identified with the Alamut Castle, Navizar Shah Castle, Shirkuh Castle, Shahrak Castle, and Shams Kalayeh Cave. Recently, Enayatollah Majidi located it on top of Mount Shatan (کوه شاتان Kūh-e Shātān; 36°28′34″N 50°36′25″E / 36.4762463°N 50.6069645°E / 36.4762463; 50.6069645) near Khoshk Chal.

The fortress was surrendered by Imam Rukn al-Din Khurshah, who was residing there, to the invading Mongols under Hulagu Khan and was subsequently demolished. This was followed by surrender of Alamut and almost all other strongholds and the disestablishment of the Nizari state.