Their civilizations developed pretty slow huh, because when Grim'War first appeared in that world, the world already looks pretty civilized around maybe the middle age era maybe before, but then he says he didn't take anyone for thousand(s) of years. On top of that the first archmage is let's say at least a couple hundred and at most a few thousand years ago (I don't remember if it was actually stated how long ago it was). So with at the very least 3000 years their civilizations are still at that level. Like it's not like in 66666 years dark mage where it was revealed that the gods resets their civilizations