The black mountain (Y Mynydd Du)is a range of peaks at the Westernmost edge of the Brecon Beacons consisting on the Carmarthenshire fans and edging over the border into Brecknockshire, stretching from Amanford (at the end of my valley) to Sennybridge it was mentioned way back in the dark ages and my spot featured in the Mabinogi, specifically in Arthur's hunt for the legendary boar the Twrch Trwyth, my village's name Glanaman is derived from the old name/term Clun Amanw (yBanw) which means pastures of the boars,also further towards the Brecknock boundary, the legend of the lady of the lake and the Physicians of Myddfai (where Prince Carlo now has a residence, Llwyn Wermwd) the area was also a favoured hunting ground of my ancestors the Rulers of Deheubarth so with the later influence of the Norman squatters was sometimes known as the Black Forest.
The black mountains (Y Mynyddoedd Duon) however are a group of hills spread across parts of Powys and Monmouthshire in southeast Wales, and extending across the England–Wales border into Herefordshire.
But to confuse you further there is the Black Hill In Herefordshire which is also known as Mynydd Du
Both my brothers were born in Wales. I can't help if it I was three years premature 
