Originally Posted by
factotum
He always had the ME legendarium as a background for all his works, I think--note that the swords Glamdring, Orcrist and Sting were explicitly stated as having come from Gondolin before its fall when Elrond examines them in The Hobbit (although it's never clearly explained how those swords managed to end up in a troll cave hundreds of miles from where Beleriand used to be, or why goblins still fear them so much several thousand years after Gondolin's fall).