View from Alamut, Castle of the Assassins, out over the valley, northeast of Ghazvin, Zanjun Province, Iran. The Frankish knights who returned to Europe from the Crusades during the eleventh and twelfth centuries took with them tales of The Old Man of the Mountain, the leader of a religious sect known as the Assassins, who lived ina series of mountain fortresses near the source of the Alamut river, deep in the Alborz mountains of northern Iran.