Vikings began to raid settlements in order to loot them for treasure. Christian monasteries in the British islands were especially vulnerable to attack, because of their isolation and tendency to have no weapons.
The first account of a raid was in 787 at the Isle of Portland. Anglo-Saxons may have began burying treasure hoards to hide them from Vikings, and Vikings may have also buried treasure to protect their loot. These hoards could contain silver, coins, and jewelry.