
This failed attempt by Plantard has been exhaustively debunked by scholars and journalists alike, but Brown chose to base his claims on Plantard’s forged documents. While this is not true, the historical Priory of Sion did present a series of documents to prove the existence of a bloodline descending from Jesus and Mary Magdalene, which was later exposed as an elaborate hoax in the form of an esoteric puzzle. However, the nature of the group differs wildly from Brown’s portrayal, who claims that the Priory boasted members like Leonardo da Vinci and Victor Hugo. The existence of The Priory of Sion was indeed real, as it was a fraternal organization founded by Pierre Plantard in 1956.

Moreover, there is no historical evidence that The Knights Templar discovered the Grail and were annihilated due to the knowledge of the same (although that hasn't stopped the Holy Grail from being a MacGuffin in dozens of King Arthur movies). This poem presents the Grail as a mysterious, live-restoring cup, which is used as a reference point by Brown, who then alters the premise into claims about Jesus and Mary’s sacred bloodline. The first association between the Templar and the Holy Grail can be traced back to German writer Wolfram von Eschenbach, and his Arthurian epic poem, Parzival.
