In scattered and isolated places across Middle-earth, the dead walk, ever bound to this world by sorcery or curse.
Almost all undying beings are bound into the service of Sauron, he who forged their deathless existence.
By contrast, the spirit-folk of the Dwimorberg are tied to an altogether different fate.
When Elendil marched against Sauron, his son, Isildur, came to the Dwimorberg and obtained an oath-sworn promise of aid against the forces of Mordor from the people that lived there.
Yet when Isildur called upon the people of the mountains to fight, they scattered and fled, entombing themselves in their fortress rather than fighting in fulfilment of their promise. In rage at their betrayer, Isildur cursed them to wander the hills for all eternity until their oath was met.
To this day, their oath has yet to be fulfilled…