War of Wrath
The extreme west of Middle-earth in the First Age was Beleriand. It and Eriador were separated from much of the south of Middle-earth by the Great Gulf. Beleriand was largely destroyed in the cataclysm of the War of Wrath, leaving only a remnant coastal plain, Lindon, just to the west of the Ered Luin (also called Ered Lindon or Blue Mountains). The cataclysm divided Ered Luin and Lindon by the newly-created Gulf of Lune; the northern part was Forlindon, the southern Harlindon.