The earliest date given for a Viking raid is 787 AD when, according to the "Anglo-Saxon Chronicle", a group of men from Norway sailed to Portland, in Dorset. There, a royal official mistook them for merchants. They killed him when he tried to lead them to the king's manor to pay a trading tax on their goods. The beginning of the Viking Age in the British Isles is, however, often given as 793. It was recorded in the "Anglo-Saxon Chronicle" that the Northmen raided the important island monastery of Lindisfarne: