The Order of Assassins or simply the Assassins (, ) were a Nizārī Ismāʿīlī order and sect of Shīʿa Islam that existed between 1090 and 1275 CE. During that time, they lived in the mountains of Persia and in Syria, and held a strict subterfuge policy throughout the Middle East through the covert murder of Muslim and Christian leaders who were considered enemies of the Nizārī Ismāʿīlī State. The modern term assassination is believed to stem from the tactics used by the Assassins. Nizārī Ismāʿīlīsm formed in the late 11th century after a succession crisis within the Fatimid Caliphate between Nizār ibn al-Mustanṣir and his half-brother, caliph al-Musta‘lī. Contemporaneous historians include Arabs ibn al-Qalanisi and Ali ibn al-Athir, and the Persian Ata-Malik Juvayni. The first two referred to the Assassins as batiniyya, an epithet widely accepted by Ismāʿīlīs themselves. Overview The Nizari Isma'ili State, later known as the Assassins, was founded by Hassan-i Sabbah. The state was formed in 1090 after the capture of Alamut Castle in modern Iran, which served as the Assassins' headquarters. The Alamut and Lambsar castles became the foundation of a network of Isma'ili fortresses throughout Persia and Syria that formed the backbone of Assassin power, and included Syrian strongholds at Masyaf, Abu Qubays, al-Qadmus and al-Kahf. The Nizari Isma'ili State was ruled by Hassan-i Sabbah until his death in 1124. The Western world was introduced to the Assassins by the works of Marco Polo who understood the name as deriving from the word hashish. The rulers of the Nizari Isma'ili State were religious leaders, at first da'i and later Imams. Prominent Assassin leaders operating in Syria included al-Hakim al-Munajjim, the physician-astrologer (d. 1103), Abu Tahir al-Sa’igh, the goldsmith (d. 1113), Bahram al-Da'i (d. 1127), and Rashid ad-Din Sinan, renowned as the greatest Assassin chief (d. 1193). While Assassins typically refers to the entire sect, only a group of disciples known as the fida'i actually engaged in conflict. Lacking their own army, the Nizari relied on these warriors to carry out espionage and assassinations of key enemy figures. The preferred method of killing was by dagger, nerve poison or arrows. The Assassins posed a substantial strategic threat to Fatimid, Abbasid, and Seljuk authority. Over the course of nearly 300 years, they killed hundreds – including three caliphs, a ruler of Jerusalem and several Muslim and Christian leaders. The first instance of murder in the effort to