A native Briton kingdom that, from about the 6th century, had extended over the basin of the River Clyde and adjacent western coastal districts, the former county of Ayr. Its capital was Dumbarton, “fortress of the Britons,” then known as Alclut. The name Strathclyde was not used until the 9th or 10th century.

[Encyclopaedia Brittanica https://www.britannica.com/place/ accessed 09Oct2109]

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