: I generally think of Middle-earth as the part in which LotR takes place, Beleriand, the Rhun, the Harad, Khand, the Far East of Endor, and the big southern continent that looks like Africa. I also think of Aman and the "East Land" as separate from Middle-earth. I don't know what to make of that "Dark Land" to the south of what Karen Fonstad labels "Palisor" in her Atlas.

I believe that all Arda is Middle-earth. They are one and the same. Beleriand was mostly gone by the time of the Third/Forth ages having been sunk "below the sundering seas" with the Changing of the World at the end of the First Age when modern history began. The only part that remains is the sliver West of the Blue Mountains (?) the Lune etc where the Grey Havens are. As for Aman, this is definitely not part of Arda nor even Menel (the Heavens). Tolkien stated that during the Changing of the World, the "Uttermost West" was removed forever from the "Circles of the World", which the Silmarillien implies means the whole of creation - the universe. The Ainur who didn't go down to the world and remained with Iluvatar exist in this realm. As do Sauron and Morgoth who didn't have the power/spirit left to reform, however it was implied that they were very far away in this realm (don't know where or if that even has any meaning, but I think it was referred to as The Void) and obviously didn't reside in the Halls of Iluvatar (I think that's what it was called). So there were the Halls of Iluvatar that existed in the Void where Iluvatar and the rest of the Ainu resided, the Void itself where Sauron and Morgoth were and probably many other evil spirits that were trapped outside of a form, and hidden somewhere in the Void that only Iluvatar never where was the Eternal Flame (is that what it was called?) which was the well spring of life and creation for him, and nothing created without it was truely alive - like the Dwarves originally created by the Vala whathisname (!) the smith begins with A, were alive whilst his thoughts were turned their way, but stopped again when he thought of something else. Iluvatar, took them into his care and put them to sleep until the appointed hour then gave them true life. Also in the Void was the World which seems to describe the real Universe not just Earth. The World (Circles of the World) included orginally Aman, Arda and Menel - Valinor/Erresea, etc, Middle-earth, and the Heavens (presumably space), then Aman was removed to the void, but where is anybodies guess!
Colin