There was originally going to be an area in Divinity 2 containing elves and dwarves, at least, but that got cut during development (late enough there wasn't much of an explanation put in the game for their absence, or references to them in other areas, etc).
There was also going to be a swamp (
screenshot 588KB), also cut at some point.
Imps are native to Rivellon, being created by one of the seven gods, according to Divine Divinity lore (and Zix Zax himself, if you talk to him in the Council Hall). They also exist in other realms, like Nemesis, where Beyond Divinity is set.
