the literary and historical sources include: Alt Clut or Ystrad Clud – a kingdom centred at what is now Dumbarton in Scotland. Later known as the Kingdom of Strathclyde, it was one of the best attested of the northern British kingdoms. It was also the last surviving, as it operated as an independent realm into the 11th century before it was finally absorbed by the Kingdom of Scotland. Elmet – centred in western Yorkshire in northern England. It was located south of the other northern British kingdoms, and well east of present-day Wales, but managed to survive into the early 7th century. Gododdin – a kingdom in what is now southeastern Scotland and northeastern England, the area previously noted as the territory of the Votadini. They are the subjects of the poem Y Gododdin, which memorialises a disastrous raid by an army raised by the Gododdin on the Angles of Bernicia. Rheged – a major kingdom that evidently included parts of present-day Cumbria, though its full extent is unknown. It may have covered a vast area at one point, as it is very closely associated with its king Urien, whose name is tied to places all over northwestern Britain. Minor kingdoms and other regions Several regions are mentioned in the sources, assumed to be notable regions within one of the kingdoms if not separate kingdoms themselves: Aeron – a minor kingdom mentioned in sources such as Y Gododdin, its location is uncertain, but several scholars have suggested that it was in the Ayrshire region of southwest Scotland. It is frequently associated with Urien Rheged, and may have been part of his realm. Calchfynydd ("Chalkmountain") – almost nothing is known about this area, though it was likely somewhere in the Hen Ogledd, as an evident ruler, Cadrawd Calchfynydd, is listed in the Bonedd Gwŷr y Gogledd. William Forbes Skene suggested an identification with Kelso (formerly Calchow) in the Scottish Borders. Eidyn – this was the area around the modern city of Edinburgh, then known as Din Eidyn (Fort of Eidyn). It was closely associated with the Gododdin kingdom. Kenneth H. Jackson argued strongly that Eidyn referred exclusively to Edinburgh, but other scholars have taken it as a designation for the wider area. The name may survive today in toponyms such as Edinburgh, Dunedin, and Carriden (from Caer Eidyn), located fifteen miles to the west. Din Eidyn was besieged by the Angles