[Boron]

You could start a game with both nations and wait until you get all heroes . Do it for all themes also . Iirc there are some additional hints about the history of ermor + pythium in the descriptions of the heroes .

Basically i would say the history is that Ermor was the Roman empire and then crumbled and Nations like Marignon and Ulm got free ( at least the nation description indicates it ) . Pythium is what Byzantine was .