We know that Middle-earth was archaic Europe. The dates provided by Tolkien may be up for debate, but the continent the War of the Ring took place on is certain... right?
Or is it? What if the Red Book of Westmarch didn't include a map? We know that the map of Beleriand went through several very different iterations - clearly because Tolkien was trying to reconstruct something he didn't have in front of him. And since that is the case: why should we believe Tolkien when he says it's ancient Europe?
There is another theory. It looks something like this:
This theory has not been the subject of much debate - but if it had been, this is what the discussions would have looked like: