The Aergosian Empire was the largest nation to date to have existed on the Idryllian continent. Centred on the city of Aergoth, the empire first began to coalesce in the late Age of Settlement, before reaching its prominence in the Age of Knowledge with the aid of the Arcane Society.
At its peak, it controlled the entire Southrealm, established colonies on the Western Isles, and most of Northrealm to the Northern Forest. While Aergosians dominated within the empire, it also contained the other human races, as well as the Gear Gnomes, Scaled Folk, and Tel-Kabal.
Late in the Age of Knowledge, the First Daemon War would threaten the Empire, and the Companions would reveal the corruption of the Arcane Society, causing much of the empire's military might to break down. Even in times prior, the far flung northern reaches had begun to rebel.
The Empire is effectively stated to have ended in full when the Emperor was assassinated early in the Age of Wars, though the city-state of Aergoth would persist (locked in a war with Laycin, the city of the now-exiled Arcane Society) up until the Age of Cataclysm, when the Night of Falling Stars destroyed much of the remainder of it.