The Black Mountains ( or sometimes ) are a group of hills spread across parts of Powys and Monmouthshire in southeast Wales, and extending across the England–Wales border into Herefordshire. They are the easternmost of the four ranges of hills that comprise the Brecon Beacons National Park, and are frequently confused with the westernmost, which is known as the Black Mountain. The Black Mountains may be roughly defined as those hills contained within a triangle defined by the towns of Abergavenny in the southeast, Hay-on-Wye in the north and the village of Llangors in the west. Other gateway towns to the Black Mountains include Talgarth and Crickhowell. The range of hills is well known to walkers and ramblers for the ease of access and views from the many ridge trails, such as that on the Black Hill (Herefordshire) at the eastern edge of the massif. The range includes the highest public road in Wales at Gospel Pass, and the highest point in southern England at Black Mountain. Name In his description of a Blak Montayne, the antiquarian John Leland refers to a massif extending between Carmarthen and Monmouth i.e. what is now considered to be the Brecon Beacons in the wider modern sense of that term, thus including the Black Mountain far to the west and the intervening high ground. There is a suggestion too that the names Hatterrall Hill and Mynydd y Gader may also once have been used to apply to the entire range of the Black Mountains though the former later became confined to the vicinity of its eastern ridge. The latter is now recognised in Pen y Gader-fawr (Pen y Gadair Fawr) and Gader Fawr (Gadair Fawr); names applied to the hill at SO 229288. Cadair, mutated to 'gadair' and anglicised as 'gader', means 'seat' or 'chair' in Welsh. The Welsh name for these hills is traditionally Y Mynydd Du ('the black mountain') though in more recent times the name Y Mynyddoedd Duon ('the black mountains') has been used, being a retranslation from the English. Mountains The highest mountain in the group is Waun Fach whose heavily eroded peat summit plateau attains a height of . Its secondary summit Pen y Gadair Fawr at has a more distinctive peak shape. On the eastern ridge, the peak of Black Mountain stands on the Wales-England border, and is the highest point in England south of Great Whernside in