Did you miss the part where it is highlighted that the only reason they became an Empire is out of necessity because they were repeatedly invaded, conquered and almost wiped out? That even after being forced out of fertile territory and into the frozen wasteland, they were still forced to fight for every last little scrap?
The Reaper quests go deeper into their origins, though Garlemald as a zone did not reveal anything that wasn't already outlined in the lore book and side quests. It simply brought it to the forefront.
