Cûm Taran (Du. "Vale of thunder") ,so named because its great elevation frequently brought thunder clouds near to the earth, formed part of the highland plateau at the center of the Belfalas peninsula, enclosed by the two great arms of the Ered Torthonion. Divided from the larger Nan Roechbin by a secondary mountain ridge, Cûm Taran served as the sacred ground and barrow field for the five Daen clans of the Ered Torthonion that remained true to the Dúnedain during the War of the Last Alliance, and so escaped the curse of the Oathbreakers.
Each clan possessed a single, great barrow, containing the remains of the headman to whom it traced its lineage, surrounded by numerous lesser or unmarked, common graves for the members of that clan. Like all burial places of the descendants of the Daen Coentis, the barrow field of Cûm Taran dated back only to the beginning of the Third Age (since, prior to that time, Lugh Gobha had always functioned as the principal site of burial). Because of the site's origin and the clans' implicit renunciation of their ancestral loyalty, the one surviving Oathbreaker clan of Belfalas did not possess a barrow site at Cûm Taran, preferring instead to identify itself with the site of Galibur, whence the first King of the Mountains had his ancestry.
Because the whole of the vale was considered to be sacred ground, none of the clans had a permanent campsite there (though one of the five grazed its sheep along the mountain slopes on the eastern rim of the valley). Three circles of standing stones marked the boundaries of the sacred ground, and one of the beacon towers of the prince was perched upon the low ridge separating the valley from the Nan Roechbin to the north. Several abandoned mine shafts punctuated the mountain walls of Cûm Taran, attesting to earlier exploitation of the region by the Daen Coentis
- MERP:Southern Gondor - The Land