Pretty much what Edi has said in some threads. WIth the change from dom2 themes into dom3 eras some inconsistencies have emerged.
I would like to make some changes, but it would probably affect both ongoing games as well as general setup, balance and the manual.
So currently nations are consistent only regarding to themselves. At times I dream of making more eras, but that would probably cause a lot more problems than it would solve.
LA ermor should be in the MA and both MA ULM and Marignon should be results of Ermors fall. Edis suggestion with the MA Ermor made LA might work with some changes. This is an idea I'm quite fond, but I'm not sure if a fix would be good. A problem might be the troops predating the ashen empire that is not in the EA Ermor (censors etc). If there was more eras I could have the current MA Ermor with its censors before ashen and keep ashen at the time of Marignon.
As you see I'm not entirely satisfied with the overall historical consistency
All three (Hinnom, Ashdod, Gath) are predating Christianity, and should be in Mythical and early eras if placed in real world history.
I'm starting to think that a reason for inconsistencies and stuff as well as SP gripes, is the lack of scenarios. If there was a premade map with a background story, a fully developed ermor and a couple of fringe states available for the new player, or another map where ermor just had fallen with Marignon and Ulm fighting to stall the dead, SP could be more fun and probably more challenging.
I wonder why there are so few scenarios out there. Probably because we didn't include any of our own in dom3.