The Prieure prieuré De, sion translated From french As priory Of, sion is a name given to multiple, groups both real and. Fictitious the most controversial is a fringe fraternal, organisation founded and dissolved In france in (1956 abiding by the 1901 French law Of) associations By Pierre. plantardhe Priory of Sion myth has been exhaustively debunked by journalists and scholars as one of the great hoaxes of the 20th century.