The range stretches approximately from Ammanford in the south-west to Sennybridge in the north-east, and consists mostly of Old Red Sandstone and Limestone. It is part of the recently-created Fforest Fawr Geopark.

The Black Mountain should not be confused with the Black Mountains in the east of the National Park, nor with a 702 metre summit in the Black Mountains that is confusingly also called Black Mountain.