Demetae

The Demetae were a Celtic tribe in Britain before the Roman invasion. The tribal territory comprised the present-day counties of Pembrokeshire and Carmarthenshire in southwest Wales. They were also named by Dyfed.

They are mentioned in Ptolemy's Geographia as western neighbors of the Silures. He names two of their towns; Moridunum (today's Carmarthen ) and Luentinum (identified as the Dolaucothi - gold mines ). They are not mentioned in Tacitus reports on the Roman wars in Wales, as he is more focused on the Silurian and Ordovicer.

Vortiporius, " the tyrant of Demetae ", is one of the kings who sentenced Gildas in the 6th century in De Excidio et Conquestu Britanniae. This indicates probably the post-Roman small kingdom of Dyfed.