Carmarthenshire is the largest of the historic counties of Wales, and known to have been inhabited since prehistoric times. Carmarthen, its county town, with its Roman fort, claims to be the oldest town in Wales.

Carmarthenshire was a heavily disputed territory between the Welsh and the Normans in the 12th and 13th centuries, and many of the castles and forts dotting its landscapes date from this period. They include ruins at Carreg Cennen, Dinefwr, Dryslwyn, Laugharne, Llansteffan and Newcastle Emlyn, as well as the slightly better-preserved Kidwelly Castle. Carmarthen Castle, meanwhile, saw further fighting during both the Wars of the Roses and the Civil War, when it was captured twice by the Parliamentary forces, and ordered to be dismantled by Oliver Cromwell.

In these more peaceful times, the economy of the county is mainly agricultural (the 19th-century Rebecca Riots, in which local farmers and agricultural workers protested against higher tolls and taxes, started in Carmarthenshire), and its fertile farmland is known as ‘The Garden of Wales’. A more literal garden, the National Botanic Garden of Wales, opened in 2000.