My understanding of the lore is basically
"Valenwood is alive and will kill you for basically anything, including burning deadwood, the Bosmer have a 'special relationship' that let's them exist by virtue of knowing exactly what's permitted(very little) and what's not(everything else)"
"Black Marsh is alive and will kill you, the Argonians live there by virtue of literally being Black Marsh's kids and agents"
"Elsweyr is fucked and some of that is because ALL the Khajit live there, including the Khajit that look like tigers and the ones that look like housecats, good luck figuring out which cats won't kill you and which cats you won't be executed for murdering(hint: these are not actually exclusive categories)."
Every other Province has some population of every race, and even the three mentioned kind of do. I'd also like to point out that Skyrim is, in fact, ruled entirely by Nords, sooooooo.
Also, Ulfric ruined a good thing by demanding open Talos worship WAAAY too soon, before then the Imperials just didn't actually enforce the ban and the Thalmor fumed, afterwards the Empire HAD to let Thalmor in to enforce it instead because they were NOT yet ready to go to war with the Thalmor.
Oh, and if you think "wouldn't that just go like the last one?", well, actually, NO. See, last time the Thalmor had a Daedric Artifact that gave them perfect information and communication, that got removed from their possesion before that last battle they lost outside the Imperial City, and they don't have it any more. Empire at peak vs Thalmor at peak without that artifact would STILL be a win for the Empire even without Hammerfall or Elsweyr.