Cumbrian Mountains in the context of "Windermere"

Strathclyde (Welsh: Ystrad Clud, "valley of the Clyde"), also known as Cumbria, was a Brittonic kingdom in northern Britain during the Middle Ages. It comprised parts of what is now southern Scotland and North West England, a region the Welsh tribes referred to as Yr Hen Ogledd (“the Old North"). At its greatest extent in the 10th century, it stretched from Loch Lomond to the River Eamont at Penrith. Strathclyde seems to have been annexed by the Goidelic-speaking Kingdom of Alba in the 11th century, becoming part of the emerging Kingdom of Scotland.

In its early days it was called the kingdom of Alt Clud, the Brittonic name of its capital, and it controlled the region around Dumbarton Rock. This kingdom emerged during Britain's post-Roman period and may have been founded by the Damnonii people. After the sack of Dumbarton by a Viking army from Dublin in 870, the capital seems to have moved to Govan and the kingdom became known as Strathclyde. It expanded south to the Cumbrian Mountains, into the former lands of Rheged. The neighbouring Anglo-Saxons called this enlarged kingdom Cumbraland. We do not know what the inhabitants called their polity, though it may have been referred to as “Cumbria.”