The Brecon Beacons National Park was established in 1957, the third of the three Welsh parks after Snowdonia in 1951 and the Pembrokeshire Coast in 1952. It stretches from Llandeilo in the west to Hay-on-Wye in the northeast and Pontypool in the southeast, covering 519 square miles and encompassing four main regions – the Black Mountain in the west, reaching 802 metres (2631 feet) at Fan Brycheiniog, Fforest Fawr and the Brecon Beacons in the centre, including the highest summit in the park and in South Wales at Pen y Fan 886 metres (2,907 feet) and the confusingly named Black Mountains in the east, where the highest point is Waun Fach 811 metres (2,661 feet).
Due to the relative remoteness and harsh weather of some of its uplands, the Park is used for military training. UK Special Forces, including the SAS and SBS hold demanding selection training exercises here, such as an exercise called the Fan dance. The infantry regiments of the British Army train at Sennybridge, where NCO selection also takes place.