The attack on Lindisfarne, described in Alcuin’s letters, was traditionally seen as the first Viking raid on Britain and Ireland and therefore marked — according to the ‘Shetelig axiom’ — the start of the so-called ‘Viking Age’. Scholars now believe that contact with Scandinavia, both trading and raiding, preceded this point.
Ellis, Caitlin. "The Vikings sack the island abbey of Lindisfarne, off the northeastern coast of England". The Literary Encyclopedia. First published 04 January 2016
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6881, accessed 14 February 2016.]