Between 1961 and 1984, Plantard contrived a mythical pedigree for the Priory of Sion claiming that it was the offshoot of a real Catholic religious order housed in the Abbey of Our Lady of Mount Zion, which had been founded in the Kingdom of Jerusalem during the First Crusade in 1099 and later absorbed by the Jesuits in 1617. The mistake is often made that this Abbey of Sion was a Priory of Sion, but there is a difference between an abbey and a priory. Calling his original 1956 group Priory of Sion presumably gave Plantard the later idea to claim that his organisation had been historically founded by crusading knight Godfrey of Bouillon on Mount Zion near Jerusalem during the Middle Ages.