After reading Tolkien's Letters last year, I was intrigued by his reference in his letter to Rhona Beare, to Ancient Egypt, concerning the crown worn by Elendil. I decided to try and find out more, and after doing some reading (both on the net and my partners large collection of books on the subject), thought I saw some similarities between the Númenorean dynasty and the 18th and 19th dynasties of Ancient Egypt.

 It's my opinion that Tolkien greatly extended the Line of Kings (as found in the Annals of Kings and Rulers of the Appendix of LotR), in part, to facilitate the parallel with this immensely long-lived, monumentally influential culture. There were also other linguistic reasons too I believe, but that's another story. I don't seek to draw any conclusions, make you're own mind up.