Old Man of the Mountain (nickname)

The Old Man of the Mountain (Latin: Vetulus de Montanis)(Persian: پیرِ کوهستان, pir-e koohestan), is the expression first used by Marco Polo in a passage from Book of the Marvels of the World, to indicate Hasan-i Sabbah, the grand master of the "Order of Assassins" (the Nizari Ismaili state) who was based in the mountain fortress of Alamut. It later became a common name used by the Crusaders.

Subsequently, this nickname was given to various Isma'ili successors of Hassan, in Syria, particularly, for example Rashid al-Din Sinan, the da'i (missionary) and a leader of the Syrian branch of the Nizari Isma'ili state.