Disclaimer: Of course I know that all nations in Dominions 2 are fiction/fantasy.
Man: Norman maybe. The description (conquered a kingdom/strict (feudalism) fits pretty well and the knight unit has a norman shield and IIRC even chain mail armor like the knights on the Bayeux tapestry.
Ermor: Rome. The names and descritptions of the legionary units in Broken Empire and their position on the battlefield are correct. But Soul Gate got it wrong: Tribunes, Senators and Consuln weren't religious leaders.