The Kingdom of Dyfed, 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. The medieval Irish narrative, The Expulsion of the Déisi, attributing the kingdom's founding to Eochaid, son of Artchorp, being forced across the Irish sea, in the 5th century; his descendants founding the line of the kings of Dyfed, down to "Tualodor mac Rígin". The Normans invaded Wales, and by 1138 incorporated Dyfed into a new shire called Pembrokeshire after the Norman castle built in the Cantref of Penfro and under the rule of the Marcher Earl of Pembroke.

Wales is a country that is part of the United Kingdom. It is bordered by the Irish Sea to the north and west, England to the east, the Bristol Channel to the south, and the Celtic Sea to the south-west. As of the 2021 census, it had a population of 3,107,494. It has a total area of 21,218 square kilometres (8,192 sq mi) and over 2,700 kilometres (1,680 mi) of coastline. It is largely mountainous with its higher peaks in the north and central areas, including Snowdon, its highest summit. The country lies within the north temperate zone and has a changeable, maritime climate. The capital and largest city is Cardiff.