It's a small world
The Human Empire was as vast as it was diverse. Ever the opportunists, Humans spread over much of the southern part of the continent and some of the southern seas, going wherever trade and fortune would take them.
The Empire had to retreat into itself following the monster insurgences. Most of its surviving settlements are centred on the old commercial backbone of the Empire that runs north-south from the Pirate Confederation to the densely-populated regions in the south (notably the old capital, Lazarus).