Cartographers Guild: beyond the known realms

Just because you have a map of the known world doesnt mean there isnt a whole lot more just beyond the edge of the map.
Even in The Last Airbender the map of the world known to 'humans' is only half the planet.
First off...maps are drawn by the people at the centre of the map. They are not drawn by the people living on an island at the far edge.  Explorers venture out from the middle seeking knowledge of the unknown. At-lendh-eis (Altantis) is a year over the frozen lands. That should give you some hint as to how far people are willing to travel.
Abundant resources, rare materials, territory. These are the things that build empires.