After the inundation of Beleriand at the end of the First Age, the Dwarf-clans of Nogrod and Belegost left their ruined cities in the Blue Mountains and migrated eastwards, and many of these migrants settled in Khazad-dûm. Those clans are not named in canonical sources, but the essay Of Dwarves and Men (in The History of Middle-earth volume 12) identifies them as the Firebeards and the Broadbeams.