A kingdom in central Wales that was, in the Arthurian period, said to have been ruled by legendary kings such as Cadell I, Cyngen I and Brochmail I (Brochmael I). It is rarely mentioned in Arthurian legend.

The bard Taliesin is connected to its court.

According to The Place-names in Wales (1912), Powys included the counties of Merioneth (Meirionydd), and Montgomery. The word powys is thought to mean a state of rest. Pwyso means to lean; gorpkwyso, to rest. Powys Fadog may mean Madoc’s settlement or rest.