An early British kingdom that flourished between the fifth and ninth centuries and continued as a sub-kingdom of Scotland until the eleventh century. Along with Wales itself and West Wales or Cornwall, Strathclyde was one of the enclaves where Brythonic kings continued to hold sway.
Location
The south-west corner of modern Scotland, or roughly where the modern region of Strathclyde is today, except that at its fullest extent the kingdom of Strathclyde stretched from the Firth of Clyde in the north, to the river Derwent in Cumberland (encompassing what was once northern Rheged )
Name
Strathclyde may well have been the simply the name appended to the kingdom by the Scotti. The earliest historical references that do exist refer to the kings of Alt Cluid, Clyde Rock, the capital of the kingdom. To the local Brythonic speaking inhabitants it may have been known as Ystrad Clud, the valley of the Clyde, or possibly under a different name altogether.
History
The kingdom of Strathclyde evolved from the tribal territories of the Damnonii, themselves part of the confederation of northern tribes known as the Brigantes and was centred on the citadel of Alt Cluid. Ceretic Guletic is the first recorded king of Strathclyde, who ruled sometime in the mid to late fifth century, his appellation Guletic signifying his reputation as the founder of the kingdom.
From the genealogies preserved by their southern cousins in Wales we can derive something of the sequence of rulers but in truth the recorded history of Strathclyde is scant and fragmented. There are no surviving native records, and all we know comes from a few scattered references in the surviving Scottish and English records.
What we can say is Strathclyde's history was dominated by warfare and territorial struggle against neighbouring kingdoms; not only was there the struggle to remain independent in the face of Northumbria eager to extend its dominion northwards, there was also a three way struggle for dominance in the north with the kingdoms of Dal Riada and Pictavia.
The defeat at Nechtansmere in 685 effectively ended Northumbrian hopes of extending its control northwards, but in the struggle between the three northern kingdoms, kings came and went, battles were fought and lost, and sometimes Strathclyde and sometimes Dal Riada and sometimes Pictavia held the upper hand.
In the end it was the intervention of the Vikings in the ninth century that changed everything, playing a significant role in uniting Dal Riada and Pictavia under one king. The beginning of the end for Strathclyde was in the year 870 when As the Annales Cambriae recorded,
The fortress of Alt Cluid was broken by the gentiles
that is, stormed and captured by Olaf, the
Viking king of
Dublin. It is generally presumed that this was with at least the tacit support of
Constantine I, then king of the united kingdoms of
Dal Riada and
Pictavia, as it is clear that
Constantine I took this as an opportunity to extend his influence south over Strathclyde.
The reigning king of Strathclyde, Arthgal map Dumnagual was captured and taken to Dublin where he was eventually killed; his son Rhun map Arthgal, who had married one of the daughters of Kenneth mac Alpin and was therefore brother-in-law to Constantine I succeeded him.
Eochaid map Rhun is really the last British king of Strathclyde. He allied himself with Giric, one of the nephews of Kenneth mac Alpin, who had seized the crown of the Scots in 878. But a year later, Donald I had defeated them both and established himself as overlord of both the Scots and the Strathclyde Welsh. There is evidence to suggest that at most of the native nobility then fled south into exile in Gwynedd but Strathclyde seems to have continued as a semi-autonomous sub-kingdom of Scotland for another century or so with a (rather confused) king list of its own.
It is not until 1018, and the rule of the modernizer Malcolm II, and in particular his defeat of the English at the Battle of Carham and the consequent recovery of Lothian, that the notion of a separate Strathclyde disappeared, and became subsumed within the kingdom of Scotland.