The Erilorian Empire, or Kingdom of Erilor, was the original kingdom of the elves. It was a united mass of land in Greater Galwyndor. Its establishment was the epoch event marking the beginning of standard dating for them, which is still in use today.
Erilor eventually divided into the several nations of elves governed by three distinct kingdoms: Enenthal, Erith, and Lorithi. The Aerylothian Empire would later take inspiration from this one, even in the end when the Empire split.
Notes
The date format still in use today came from the Veninar, who taught it to the humans after making contact with them.