(You) are the key.
Keep diggin fren
'The real task of the nine knights was to carry out research in the area [ of the second temple, Herod's Temple] in order to obtain certain relics and manuscripts which contain the essence of the secret traditions of Judaism and Ancient Egypt…]
Generally, I think the Priory of Sion is an older order with older roots then what you find on Google.
Priory of Sion can be traced back to Gnostic adept Ormus, first century AD. Adaptation of esoteric Christianity & pagan rituals… → Cross & Rose.
The Templars adapted the cross as their emblem. Founded around the 11 century when Muslim denied Christian pilgrims access to Jerusalem.
Rose emblem was adopted later by the Rosicrucian.
The Rosicrucian connection relates more to modern revitalization of enlightenment thinking and pagan fertility worship at around 14th to 16th C.
This also relates to Adam Weishaupt and the Jesuits.The good ole hegelian dialectic.
Also, there are many overlapping connections to Freemasonry most notably.
What were they looking for and what did they find? The Holy Grail, the Ark of the Covenant?
Who knows?