 Dumbarton was the capital of the Kingdom of Strathclyde and this was clearly a major assault which may have brought the whole of mainland Scotland under temporary Ui Imair control.Three years earlier Vikings had seized Northumbria, forming the Kingdom of York and subsequently conquered much of England except for a reduced Kingdom of Wessex, leaving the new combined Pictish and Gaelic kingdom almost encircled.Amlaíb and his brother Auisle "ravaged the whole of Pictland and took their hostages" and later occupied this territory for a protracted period.