Page "Causantín mac Cináeda" Paragraph 7

In 870, Amlaíb and Ívarr attacked Dumbarton Rock, where the River Leven meets the River Clyde, the chief place of the kingdom of Alt Clut, south-western neighbour of Pictland.

The siege lasted four months before the fortress fell to the Vikings who returned to Ireland with many prisoners, " Angles, Britons and Picts ", in 871.

Archaeological evidence suggests that Dumbarton Rock was largely abandoned and that Govan replaced it as the chief place of the kingdom of Strathclyde, as Alt Clut was later known.

King Artgal of Alt Clut did not long survive these events, being killed " at the instigation " of Causantín son of Cináed two years later.

Artgal's son and successor Run was married to a sister of Causantín.