|Steve Edwards' website|
The Vikings were not primarily barbaric plunderers, but opportunists. Certainly, they had no moral difficulty with plunder when it was the best opportunity.
In Ireland, where monasteries were the richest opportunity, Viking plunder fell against the backdrop of plundering between monasteries themselves.
The Vikings not fully Christianized, not "from around here," and employing different methods of attack, were of course "barbarians." Whether or not they were more vicious than the natives is hard to know. The Dunmore Cave incident certainly shows a brutality known only in the most vicious form of genocidal war.
But the Vikings, however horrible or "more horrible" than the Irish, played many roles beside that of marauder.
They were, as everywhere, a commercial people. They traded when they could. They marrauded when that was more practical.
They dealt in treasures, food, animals, and people. People, they took for either slave trade or ransom; depending on the "value" of the person to the robbed community.
This, too, the Irish had already been doing.