The Nuttall Encyclopedia
Old Man of the Mountain
A name given to Hassan ben Sabbah, the founder in the 11th century and his successors of a formidable Mohammedan dynasty in Syria, whose residence was in the mountain fastnesses of the country, and whose following was known by the name of Assassins (q. v .).
Wood, James, ed. Entry for 'Old Man of the Mountain'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/o/old-man-of-the-mountain.html. Frederick Warne & Co Ltd. London. 1900.