Norse mythology, Celtic literature, English folklore, everything that Tolkien was an expert in went into his stories. Numenor was his take on Atlantis, a Greek/Egyptian legend. But it wasn’t all about war; just the interesting bits.
I got beguiled by the constant traces of fallen civilizations and lost ages stuff, when I read The Hobbit. Was thrilled that there was a ‘sequel’. Read it a few times (5, 6?) when a teen, then refreshed my experience when I heard there was a movie coming out. I skipped sections that I figured they’d skip (the Old Forest with Tom Bombadil, Goldberry, the Barrow Downs; after the first couple of times I always skipped that anyway, resumed reading where they encountered the ‘trolls’, then went to Weathertop, etc). I got a better or different experience and reactions to the books as an adult.