At the 2001 census, Mountain Ash had a population of 7,039. The Mountain Ash geographical area incorporates and includes the districts and villages of Penrhiwceiber, Cefnpennar, Cwmpennar, Caegarw, Darranlas, Fernhill, Glenboi and Newtown and Miskin. Mountain Ash lies within the historic county boundaries of Glamorgan.
The first three maps are provided by A Vision of Britain through Time
These maps were found on Wikimedia Commons
These maps of Glamorgan post-1974 were found on another site and are very useful for sorting out the up-to-date geography of the area