An Elven realm in the Second Age, also known as Hollin, lying west of the Misty Mountains near the gates of Moria. Home to the Elven-smiths led by Celebrimbor, it was here that the Rings of Power were forged under the guidance of Sauron in his fair disguise as Annatar. Sauron destroyed Eregion when the Elves discovered his treachery, and by the Third Age only ruins remain.