The Community Assembly of South Wales is located in the densely populated region of Wales in the southwest of the British Isles, bordering England to the east and the Bristol Channel to the south. It includes the capital city, Cardiff, along with Swansea and the South Wales Valleys, generally covering the historic counties of Glamorgan, Monmouthshire, Carmarthenshire and Pembrokeshire.

Between the Statute of Rhuddlan of 1284 and the Laws in Wales Act 1535, crown land in Wales formed the Principality of Wales. This was divided into a Principality of South Wales and a Principality of North Wales. The southern principality was made up of the counties of Ceredigion and Carmarthenshire, areas that had previously been part of the Welsh kingdom of Deheubarth or the southern land. The legal responsibility for this area lay in the hands of the Justiciar of South Wales based at Carmarthen. Other parts of southern Wales were in the hands of various Marcher Lords. 

The Laws in Wales Acts 1542 created the Court of Great Sessions in Wales based on four legal circuits. The Brecon circuit served the counties of Brecknockshire, Radnorshire and Glamorgan while the Carmarthen circuit served Cardiganshire, Carmarthenshire and Pembrokeshire in the west. Monmouthshire (in the east of South Wales) was attached to the Oxford circuit for judicial purposes. These seven southern counties were thus differentiated from the six counties of north Wales. 

• Simon Foster
• Susan Jones
• Gruffydd Meredith