The kingdom was ruled from Dumbarton Rock, "Alt Clut", the Brythonic name of the rock, until around 870 when the rock was captured and sacked by Norse-Gaels from the kingdom of Dublin after a four-month siege. Thereafter the centre of the kingdom moved to Govan, previously a religious centre. The kingdom is also known as Cumbria after 870, and indeed may have ruled parts of the modern English region of Cumbria in the 10th and 11th centuries. In the 11th century the kingdom of Alba conquered Strathclyde. It remained a distinctive area, with different laws, using the Cumbric language alongside Gaelic, until the 12th century.