The Priory of Sion is a purported secret society that was founded in the late 20th century, although its origins are often linked to earlier historical claims. It gained significant attention through the book "The Holy Blood and the Holy Grail," which suggested that the group was dedicated to protecting the bloodline of Jesus Christ and Mary Magdalene. Despite its intriguing narrative, many historians and scholars consider the Priory of Sion to be a hoax. The group was revealed to be a fabrication by a Frenchman named Pierre Plantard, who created documents to support its existence. Today, it remains a popular subject in conspiracy theories and fictional works.