The earliest date given for a Viking raid is 789, when according to the "Anglo-Saxon Chronicle", a group of Danes sailed to the Isle of Portland in Dorset (it was wrongly recorded as 787). They were mistaken for merchants by a royal official. When asked to come to the king's manor to pay a trading tax on their goods, they murdered the official. The beginning of the Viking Age in the British Isles is often set at 793. It was recorded in the "Anglo–Saxon Chronicle" that the Northmen raided the important island monastery of Lindisfarne (the generally accepted date is actually 8 June, not January):