STRATHCLYDE, the name given in the 9th and loth cen turies to the British (Welsh) kingdom, which from the 7th cen tury onwards was probably confined to the basin of the Clyde, together with the adjacent coast districts, Ayrshire, etc., on the west of Scotland. Its capital was Dumbarton (fortress of the Britons), then known as Alcluith. On the south this kingdom bor dered on the territories of the Niduari Picts of Galloway, including the modern counties of Wigtown and Kirkcudbright. Strathclyde is also sometimes called Cumbria, or Cumberland, and the survival of the latter name on the English side of the border preserves the memory of a period when the territories of the northern Welsh were of much greater extent.
After the withdrawal of the Romans in the 5th century the northern Britons seem to have shown greater determination in maintaining their independence than any of the southern king doms and, according to Welsh tradition, Cunedda, the ancestor of the kings of Gwynedd, had himself come from the north. In the Historia Brittonum we read of princes of the northern Britons.
Such notices as we have of the history of Strathclyde in the 7th and 8th centuries are preserved only in the chronicles of the surrounding nations and even these supply us with little more than an incomplete record of wars with the neighbouring Scots, Picts and Northumbrians. It is probable that the Britons were allied with the Scots when Aidan, the king of the latter, invaded Northumbria in A.D. 597. In 642, however, we find the two Celtic peoples at war with one another, for in that year the Britons under their king Owen defeated and slew the Scottish king Dom nall Breac. In the same year they came into conflict with the Northumbrian king Oswio. In 649 there appears to have been a battle between the Britons and the Picts, but about this time the former must have become subject to the Northumbrian kingdom. They recovered their independence, however, after the defeat of Ecgfrith by the Picts in 685. In 711 and again in 717 we hear of
further wars between the Britons and the Scots of Dalriada, the former being defeated in both years. Towards the middle of the 8th century Strathclyde was again threatened by an alliance be tween the Northumbrians and Picts, and in 75o the Northumbrian king Eadberht wrested from them a considerable part of their territories in the west including Kyle in Ayrshire. In 756 the North Britons are said to have been forced into submission and from this time onwards we hear very little of their history.
In 870 Dumbarton was attacked and destroyed after four months' siege by the Scandinavian king Ivarr, and for some time after this the country was exposed to ravages by the Norsemen. It is believed that the native dynasty came to an end early in the loth century and that the subsequent kings belonged to a branch of the Scottish royal family. Toward the end of the reign of Ed ward the Elder the Britons of Strathclyde submitted to that king together with all the other princes of the north. In the reign of his successor Aethelstan, however, they joined with the Scots and Norwegians in attempts to overthrow the English supremacy, attempts which were ended by their defeat at the battle of Brunan burh in 937. In 945-946 Strathclyde was ravaged by King Ed mund and given over to the Scottish king Malcolm I. The fall of the kingdom was only temporary, for we hear of a defeat of the Scottish king Cuilean by the Britons in 971. In the n th century Strathclyde appears to have been finally incorporated in the Scot tish kingdom, and the last time we hear of one of its kings is at the battle of Carham in 1018 when the British king Owen fought in alliance with Malcolm II.