The royal family is really lacking in the pedigree department. They've married into the right families now, but originally the Sauds were a bunch of hicks. They allied themselves with religious outsiders on the understanding that the priests would legitimize the Saudis (vs. the much better pedigreed Hashemites [1] while the Saudis would give the priests preeminence over their rivals.

[1]: https://en.wikipedia.org/wiki/Hashemites