The Golden Sea
An infinitely large plain of grass inhabited mostly by elves and centaurs. Adventurers strike out into it looking for lost cities or ancient tombs full of treasure. Navigating it is difficult since the geography has a tendency of rearranging itself when you're not looking.
Not technically part of any nation, it lies north of Numeria and the countries barbarian tribes often wander into it.
Towns dot the border of it that cater to the adventurers that explore the sea.