Two of these labeled locations -- Minas Anor and Minas Ithil -- are places we've been before. Minas Anor is an older name for the white city of Minas Tirith, which had a front-row seat to the Battle of the Pelennor Fields in The Return of the King. And Minas Ithil is the original name of Minas Morgul, that creepy green-lit fortress that Frodo, Sam, and Gollum sneak past when the Witch King of Angmar flies out on his fellbeast to join the battle.
What's important about these two names is they were what these cities were called before the 2,000th year of the Third Age, which is when Minas Ithil was taken over by the Nazgûl and renamed. The maps have been offering up clues about this for a few weeks: the region of Rohan is labeled as Calenardhon, which is the name that land had before the horse lords came down from the north and settled it. The elf citadel of Lothlórien is labeled as Laurelindórenan -- again, its old name. The watchtower of Amon Sûl, which we know as Weathertop from The Fellowship of the Ring, is also labeled with its old name, which is the name it had when it was part of the ancient kingdom of Arthedain. What this all means is that this show likely takes place before the first "defeat" of Sauron and the dawn of the Third Age.
The biggest thing this map includes is the island of Númenor, which housed a fabulous lost civilization of Men that was destroyed after they refused to worship the one god Eru Ilúvatar and rebelled against the angelic Valar. It's a long story. Think the Doom of Valyria from Game of Thrones. Or Atlantis, which is what J.R.R. Tolkien actually based Númenor on. If the official Twitter account making a zoomed-in photo of Númenor their header is anything to go off of, we're smack-dab in the middle of every incredibly cool thing that happened three or four thousand years before the events of The Lord of the Rings. Sauron begins corrupting the Númenorians, who are busy settling Middle Earth and persecuting the Elves and being dicks to the Valar; Isildur, the King of Men who cuts off Sauron's finger in battle, is born; and a certain Ring of Power is forged.
All of that history is critical, and as Tolkien scholar Tom Shippey told Deutsche Tolkien Gesellschaft, it's something to which Amazon will be bound. "The Tolkien Estate will insist that the main shape of the Second Age is not altered. Sauron invades Eriador, is forced back by a Númenorean expedition, is [sic] returns to Númenor," Shippey said. "All this, the course of history, must remain the same. But you can add new characters and ask a lot of questions … Theoretically, Amazon can answer these questions by inventing the answers, since Tolkien did not describe it. But it must not contradict anything which Tolkien did say."
While it's necessary for Amazon to adhere to the established canon, the company essentially has creative freedom in everything left unsaid (although, according to Shippey, the Tolkien Estate does have veto power). Even for hardcore LOTR fans, there's sure to be something new.