The Frontier, as it is now referred to, was uninhabited throughout recent history. No one is completely sure why this is, but various ancient legends tell of a mass exodus of all sentient races.
These legends were enough to keep the frontier uninhabited until recently, when an expedition from Essum charted the land and found no reason why it could not be settled. Essum began to expand to the northeast, and so did their neighbor Ailan start to expand to the northwest in response. They inevitably met in the middle, and while Essum would have happily drawn the border there, then King Ervar II would only accept complete ownership of the frontier territories. A war ensued not only in the frontier, but along the main border to the south as well.
Eventually, King Ervar’s place was taken by his even-tempered son Arkvald, who signed a treaty with Essum agreeing that the territory would belong to no one, that it would be a demilitarized zone, and that any who so wished would be allowed to settle on the land.
The peace between the two nations persist while Good King Arkvald lives, but many fear the reign of his son, which draws ever closer.