The fabled continent and homeland of the elves on Eos, long since missing. Not even the Dawnborn know of its location, according to Malphas. Though elves still claim to have visited, it cannot be located by any gods or scholars. Ourea has fought since the fall of Eresséia to keep the High Ones from taking it over, as the portals such as the one from Inodan that Oris guards have overtaken the land. Her army of angels keeps it bay, and she can bring others there if required.
The origin of materials that halt Red Madness, such as Ambrosia.
Before it was lost, Eresséia was governed by the Dawnborn Axthar, though Rhinther also had a strong following there.