The short version is simple. If the next game lands in Hammerfell the writers do not need to invent the bones from scratch. They already exist across Pocket Guides, in-game histories, and a handful of novels that have been sitting on shelves since 1998.
I have been rereading the same sources every few years while we wait and the map gaps keep pointing in the same directions.
Yokuda and the sinking
The PGE1 and the book Redguards, Their History and Their Heroes both treat Yokuda as a real place that sank in ancient times. The details differ by a century or two depending on which Redguard you ask, but the mechanism is consistent: a series of earthquakes and a final cataclysm tied to the Ansei. That gives any new game a ready-made lost continent to reference without breaking canon.
The Crowns and Forebears split
This one is still live in the text. The Firsthold Revolt and several Redguard NPCs in Morrowind treat the division as current politics, not ancient history. Sentinel leans Forebear, the Alik'r nomads lean Crown, and the player can already see the friction in Redguard. No need to manufacture a civil conflict when one has been on the page for decades.
The big empty spaces
The western half of Hammerfell is barely described outside a few throwaway lines about the desert and the city of Hegathe. That is not a problem. It is an opening. The same books that name the Iliac Bay cities also leave the interior deliberately thin, which matches how Bethesda has used earlier games to fill in blanks.
Practical notes from previous titles
Redguard already gave us Stros M'kai and the old capital. Oblivion added a couple of books that mention the Warp in the West effects on Sentinel. Skyrim gave us the Alik'r warriors and their wanted posters. None of it contradicts the other. The lore team has been consistent on the big beats even while the release schedule drags on.
I keep a running note file of these references because the gaps are more useful than the filled sections. When something real happens I will update the pillar thread.
So which single book or in-game text do you treat as the strongest starting point for a Hammerfell story? And how heavily would you lean on the Ansei swords if the game actually has to show them working?