Tolkien's Middle-earth was part of his created world of Arda. It was a flat world surrounded by ocean. It included the Undying Lands of Aman and Eressëa, which were all part of the wider creation, Eä. Aman and Middle-earth were separated from each other by the Great Sea Belegaer, analogous to the Atlantic Ocean. The western continent, Aman, was the home of the Valar, and the Elves called the Eldar.