Cwm is situated in the Ebbw Vale area of Blaenau Gwent, South Wales. Surrounding towns and villages include Brynmawr, Ebbw Vale, Abertillery, Blaina, Tredegar, Rhymney, and Merthyr Tydfil. The village sits halfway along the A4046 from Rassau to Aberbeeg. The Ebbw river flows past Cwm, rising at the confluence of the Ebbw Fach and Ebbw Fawr, before joining the Usk and entering the sea at the Severn estuary.

Cwm made its name during the Industrial Revolution, when it was a central hub for coal. Several mines and colleries were opened, most notably the Marine colliery, and coal was first produced here in 1893. The collieries were all very successful, but by the 1980s the industry was beginning to decline under Thatcher's government and many in the area decided to close. The Marine colliery was the last deep mine in the Ebbw valleys and closed in March 1989.