The Daelkyr War was an invasion of Eberron by creatures from Xoriat led by the daelkyr during the Unknown, approximately nine thousand years before the present. It devastated the western part of Khorvaire.
Centered around the Shadow Marches, it ended with the defeat of the daelkyr by the united forces of the orcs of the Shadow Marches and the hobgoblins of the Empire of Dhakaan, but left both races decimated.