Carmarthenshire in the context of "Cantref Gwarthaf (Dyfed)"

The Bristol Channel (Welsh: Môr Hafren, lit. 'Severn Sea') is a major inlet in the island of Great Britain, separating South Wales (from Pembrokeshire to the Vale of Glamorgan) and South West England (from Devon to North Somerset). It extends from the smaller Severn Estuary of the River Severn (Welsh: Afon Hafren) to the North Atlantic Ocean. It takes its name from the English city and port of Bristol.

Long stretches of both sides of the coastline are designated as Heritage Coast. These include Exmoor, Bideford Bay, the Hartland Point peninsula, Lundy Island, Glamorgan, Gower Peninsula, Carmarthenshire, South Pembrokeshire and Caldey Island.

The South Wales Valleys (Welsh: Cymoedd De Cymru) are a group of industrialised peri-urban valleys in South Wales. Most of the valleys run north–south, roughly parallel to each other. Commonly referred to as "The Valleys" (Welsh: Y Cymoedd), they stretch from Carmarthenshire in the west to Monmouthshire in the east; to the edge of the pastoral country of the Vale of Glamorgan and the coastal plain near the cities of Swansea, Cardiff, and Newport.

West Wales (Welsh: Gorllewin Cymru) is a region of Wales.

It has various definitions, either covering Pembrokeshire, Ceredigion and Carmarthenshire, which historically comprised the Welsh principality of Deheubarth, and an alternative definition is to include Swansea and Neath Port Talbot, but exclude Ceredigion. The West Wales and the Valleys NUTS area also includes more westerly parts of North Wales as well as the South Wales Valleys.

The Kingdom of Dyfed (Welsh pronunciation: ['dəvɛd]), one of several Welsh petty kingdoms that emerged in 5th-century sub-Roman Britain in southwest Wales, was based on the former territory of the Demetae (modern Welsh Dyfed). The royal line was founded by Irish settlers in the 5th century. After the Norman invasion of Wales Dyfed was incorporated into Pembrokeshire. The name was resurrected for the now-defunct administrative area called Dyfed as well as in the names of some regional organisations such as Dyfed–Powys Police.

Dyfed may have originally occupied the area that bordered the rivers Teifi, Gwili and Tywi, and included contemporary Pembrokeshire, the western part of contemporary Carmarthenshire, and with the town of Carmarthen. Dyfed eventually comprised at least seven cantrefi: Cemais, Deugleddyf, Emlyn, Cantref Gwarthaf, Pebidiog, Penfro and Rhos, with an approximate area of about 2,284 square kilometres (882 sq mi).

Pembrokeshire (/ˈpɛmbrʊkʃɪər, -ʃər/ PEM-bruuk-sheer, -⁠shər; Welsh: Sir Benfro [siːr ˈbɛnvrɔ]) is a county in the south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and otherwise by the sea. Haverfordwest is the largest town and administrative headquarters of Pembrokeshire County Council.

The county is generally sparsely populated and rural, with an area of 610 square miles (1,600 km) and a population of 123,400. After Haverfordwest, the largest settlements are Milford Haven (13,907), Pembroke Dock (9,753), and Pembroke (7,552). St Davids (1,841) is a city, the smallest by population in the UK. Welsh is spoken by 17.2 percent of the population, and for historic reasons is more widely spoken in the north of the county than in the south.

Llanelli (Welsh for 'St Elli's Parish'; Welsh: [ɬaˈnɛɬi] ) is a market town and community in Carmarthenshire and the preserved county of Dyfed, Wales. It is on the estuary of the River Loughor and is the largest town in the county of Carmarthenshire.

The town is 11 miles (18 km) north-west of Swansea and 12 miles (19 km) south-east of Carmarthen. At the 2021 census the community had a population of 25,366, and the built up area had a population of 42,155. The local authority was Llanelli Borough Council when the county of Dyfed existed, and it has been under Carmarthenshire County Council since 1996.

South Wales (Welsh: De Cymru [ˌdeː ˌkəmri]) is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards to include Carmarthenshire and Pembrokeshire. In the western extent, from Swansea westwards, local people would probably recognise that they lived in both south Wales and west Wales. The Brecon Beacons National Park covers about a third of south Wales, containing Pen y Fan, the highest British mountain south of Cadair Idris in Snowdonia.

A point of some discussion is whether the first element of the name should be capitalised: 'south Wales' or 'South Wales'. As the name is a geographical expression rather than a specific area with well-defined borders, style guides such as those of the BBC and The Guardian use the form 'south Wales'. The Welsh Government, in their international gateway website, Wales.com, state that it should always be capitalised; however, they use the term to refer to a tourism marketing area which excludes the Swansea and Neath Port Talbot local authority areas (placing them in 'West Wales'). In contradiction, the style guide for the Welsh Government's main website, Gov.wales, uses 'south Wales'. It is always capitalised on motorway signs.

Carmarthen (UK: /kərˈmɑːrðən/ kər-MAR-dhən, locally /kɑːrˈ-/ kar-; Welsh: Caerfyrddin [kaːɨrˈvərðɪn], 'Merlin's fort' or possibly 'Sea-town fort') is the county town of Carmarthenshire and a community in Wales, lying on the River Towy 8 miles (13 km) north of its estuary in Carmarthen Bay. At the 2021 census the community had a population of 14,636, and the built up area had a population of 16,455. It stands on the site of a Roman town, and has a claim to be the oldest town in Wales. In the middle ages it comprised twin settlements: Old Carmarthen around Carmarthen Priory and New Carmarthen around Carmarthen Castle. The two were merged into one borough in 1546. It was the most populous borough in Wales in the 16th–18th centuries, described by William Camden as "chief citie of the country". It was overtaken in size by the mid-19th century, following the growth of settlements in the South Wales Coalfield.

The Demetae were a Celtic people of Iron Age and Roman period, who inhabited modern Pembrokeshire and Carmarthenshire in south-west Wales. The tribe also gave their name to the medieval Kingdom of Dyfed, the modern area and county of Dyfed and the distinct dialect of Welsh spoken in modern south-west Wales, Dyfedeg.