Carmarthenshire (Welsh: Sir Gaerfyrddin or Sir Gâr) is a unitary authority in the south west of Wales and the largest of the thirteen historic counties. The three largest towns are Llanelli, Carmarthen and Ammanford. Carmarthen is the county town and administrative centre of Carmarthenshire. The most populous settlement is the area in and around the town of Llanelli.
With its fertile land and agricultural produce, Carmarthenshire is known as the "Garden of Wales".
Carmarthenshire has its early roots in the region formerly known as Ystrad Tywi (Vale of [the river] Tywi) and part of the Principality of Deheubarth during the High Middle Ages, with the court at Dinefwr.
Following the Edwardian Conquest of Wales, the region was reorganized by the Statute of Rhuddlan in 1284 into Carmarthenshire.
Carmarthenshire has been spelt in other ways in the past, including:
Carmarthenshire became an administrative county with a county council taking over functions from the Quarter Sessions under the Local Government Act 1888. Under the Local Government Act 1972, the administrative county of Carmarthenshire was abolished on 1 April 1974 and the area of Carmarthenshire became three districts within the new county of Dyfed : Carmarthen, Dinefwr and Llanelli. Under the Local Government (Wales) Act 1994, Dyfed was abolished on 1 April 1996 and the three districts united to form a unitary authority which had the same boundaries as the traditional county of Carmarthenshire. In 2003, the Clynderwen community council area was transferred to the administrative county of Pembrokeshire.
Carmarthenshire was a parliamentary constituency in Wales which returned one Member of Parliament to the House of Commons of the Parliament of the United Kingdom until its representation was increased to two members for the 1832 general election.
At the 1885 general election, it was divided into two new single-member seats: Carmarthenshire East and Carmarthenshire West.