The ancient name for the kingdom of Dyfed in the south of Wales on the river Teifi. According to Geoffrey of Monmouth, the kingdom was ruled by Stater during the fifth or sixth century, the traditional time attributed to the reign of King Arthur.
Ordinary history knows nothing of the ruler Stater, and tells us of a king named Agricola who ruled there in about AD 500, and of another ruler, Vortipor, who was an old man in AD 540. Before Agricola’s time in Irish dynasty, the Uí Liatháin ruled there.
Vortigern built the fortress of Vortigern here, and retreated here after the Saxons invaded eastern Britain. After four days at the fortress, a holy fire engulfed it and killed Vortigern. It was later ruled, under Arthur, by Stater. In non-Arthurian Welsh legend, it is ruled by Pwyll and, later, his son Pryderi.
Merlin’s mother is said to come from Demetia and his grandfather, Demetrus, was the king of Demetia.