Hashshashins

14th Century painting of the assassination of Nizam al-Mulk by a hashshashin
Assassins (Arabic: hashshashin, Modern Turkish: Hashasiler, also Hashishin, Hassassin, or Hashashiyyin) is a misnomer for the Nizari Ismailis applied abusively to them by the Mustali Ismailis during the fall of the decaying Ismaili Fatimid Empire when the two streams separated from each other. In 1122 the Mustalian dynasty Fatimid caliph al-Amir referred to the Nizaris separated from them and "now firmly established in Persia and Syria", abusively as the hashishiyya "without any explanation" and "without actually accusing them of using hashish, a product of hemp".
The term hashishiyya or hashishi as used by Muslim sources is used metaphorically in its abusive sense (i.e. "irreligious social outcasts", "low-class rabble", etc.). "The literal interpretation of this term in referring to the Nizaris (as hashish consuming intoxicated assassins) is rooted in the fantasies of medieval Westerners and their imaginative ignorance of Islam and the Ismailis." These supposedly medieval fantasies were still in vogue as late as 1990 until the publication of the ground breaking book on the Ismailis by the Twelver Shia author and researcher in original documents in Arabic and Persian that had been discovered in the late 20th century concerning the Ismailis in general and the Nizari Ismailis in particular.
In time the Nizari Ismailis of Persia and Syria began to pose a strong military threat to Sunni Seljuq authority within the Persian territories by capturing and inhabiting many mountain fortresses under their first leader Hassan-i Sabbah (or Hassan bin Sabbah).
The theory that the word "assassin" was derived from the Arabic word hashishin (i.e. "users of hashish"), is now considered outdated and incorrect because it refers to the now outdated and incorrect medieval sources known to have been hostile to the Nizari Ismailis. One of the classic offenders of creating this false myth were the writings of Marco Polo in which the Nizari Ismailis were depicted as assassins. Marco Polo's sources were even worse: only hearsay sources heard by him on his travel through the Levant and Syria.
According to texts that have been found i their former fortress at Alamut, the founder of the Nizari sect, Hassan-i Sabbah, liked to call his disciples "Asasiyun", meaning people who are faithful to the Asas, meaning "foundation" of the faith. Hashashins executed those who represented a threat to the Nizari cause and Islam, but would rarely attack ordinary citizens though and tended not to be hostile towards them. They favored one single assassination than the wide bloodshed of actual combat. Genocide was not tolerated, and the hashashins believed that large political assassinations would bring peace and a true sense of security to the common people. Slaying innocents and civilian bystanders who did not need to die could spread strife and discord, in addition to ruining the name of the Nizari order.
Timeline of killings and events connected to the hashshashins
1090: Hassan-i Sabbah siezes the fortress of Alamut. His community and its branches spread throughout Iran and Syria and came to be called Hashshashin, also known as the Fedayin (Meaning 'The Martyrs', or 'Men Who Accept Death'), a mystery cult.

Artistic rendering of Hassan-i Sabbah
1092: The famous Seljuq vizier Nizam al-Mulk was murdered by an Assassin in Baghdad.
1094: Al-Mustansir dies, and Hassan does not recognize the new caliph, al-Mustali. He and his followers transferred their allegiance to his brother Nizar. The followers of Hassan soon even came at odds with the caliph in Baghdad.
1113: Following the death of Aleppo's ruler, Ridwan, the Assassins are driven out of the city by the troops of Ibn al-Khashab.
1110s: The Assassins in Syria change their strategy, and start undercover work and build cells in all cities around the region.
1123: Ibn al-Khashab is killed by an Assassin.
1124: Hassan dies in Alamut, but the organization lives on stronger than ever. — The leading qadi Abu Saad al-Harawi is killed by an Assassin.
After the death of Hassan some notable events included the following:
1126 November 26: Emir Porsuki of Aleppo and Mosul is killed by an Assassin .
12th century: The Assassins extend their activities into Syria, where they could get much support from the local Shi'ite minority as the Seljuq sultanate had captured this territory.
The Assassins capture a group of castles in the Nusayriyya Mountains (modern Syria). The most important of these castles was the Masyaf, from which "The Old Man of Mountain", Rashideddin Sinan ruled practically independent from the main leaders of the Assassins.
1173: The Assassins of Syria enter negotiations with Amalric I, King of Jerusalem, with the aim of converting to Christianity. But as the Assassins by now were numerous and often worked as peasants. They paid high taxes to local Christian landlords that Christian peasants were exempted from. Their conversion was opposed by the landlords, and this year the Assassin negotiators were murdered by Christian knights. After this, there was no more talk of conversion.
1175: Rashideddin's men make two attempts on the life of Saladin, the leader of the Ayyubids. The second time, the Assassin came so close that wounds were inflicted upon Saladin.
1192: Conrad of Montferrat, King of Jerusalem, is stabbed to death by Assassins before his coronation.
1256: Alamut fortress falls to the Mongols under the leadership of Hülegü Khan. Before this happened, several other fortresses had been captured, and finally Alamut was weak and with little support.
1257: The Mongol warlord Hülegü attacks and destroys the fortress at Alamut. The Assassin library is fully razed, hence destroying a crucial source of information about the Assassins.
Around 1265: The Assassin strongholds in Syria fall to the Mamluk sultan Baybars I.
1389: Hashshashin factions regroup in Al Karak, with the blessings of Tûmân Bey, the Mameluk monarch, and then by Shihab ud-Din II, the emir of the Anazah
1392: An Assassin allegedly stabs Ferran I d'Aragó during a ceremony of hommage in Jerusalem
1445: Tomàs Folc de Cardona captures Al Karak. All the Assassins captured are executed and their bodies displayed in all the captured Syrian cities
1483: 'Abbas Fazil is killed by an Assassin shortly after he storms one of their stranghold north of Damascus. He is the last victim attributed to the Assassins.
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