Demetia

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).