Although known as early as the eighth-century the foundation of the Assassins is usually marked as 1090 when Hasan-i Sabbah, established his stronghold in the mountains south of the Caspian Sea at Alamut. A Yemeni emigrant and an Ismaili Shiite Muslim, Hasan set the aim of the Assassins to destroy the power of the Abbasid Caliphate by murdering it's most powerful members. Hasan-i Sabbah was also known as "The Old Man of the Mountain", however, this is likely to have been a mistake in translation, since "Old Man" is the literal translation of "Sheik". Much of the current western lore surrounding the Assassins stems from Marco Polo's supposed visit to Alamut in 1273, which is widely considered mytical.
The group inspired a aura of fear out of all proportion to their power. Legends stated that the Assassins were trained used ideology and drugs (the name "assassin" is believed to be a mutation of "hashishim", or "hashish-eaters") to believe they were assured a place in paradise if they were successful in murder with their golden daggers. However, the "hashishim" name was likely given to the Assassins by their enemies, and there is no evidence that the Assassins ever used drugs for this or any other purpose.
Most of the victims of the Assassins were Muslims and also Sunnis. There were some extremely highly placed victims including Nizam-ul-Mulk. Christians were largely untouched by the depredations of the Assassins, it was not until the middle of the 12th century that they had even really heard of them, although Conrad of Montferrat - the King of Jerusalem was a victim (the Assassins may have even been hired by Richard the Lionheart).
While the Assassins murdered a large number of tyrants and princes, their overall effect was limited and indeed detrimental to the Ismailis themselves, and when the ruling Caliphates were strong enough the Assassins were destroyed - by the Mongols in Persia and the Mamluks in Syria.
Assassins is also a musical with music and lyrics by Stephen Sondheim and a book by John Weidman and was based on an idea by Charles Gilbert, Jr. It uses a revue-like style to examine the men and women who have attempted and/or succeeded in assassinating a U.S. President.
"Assassins" opened off-Broadway at Playwrights Horizons on January 27, 1991 and starred Victor Garber, Terrance Mann, Patrick Cassidy, Debra Monk, and Annie Golden. The musical was supposed to have its first Broadway production in 2001, but the show was indefinitely postponed after the events of September 11, 2001.
See also: assassin.