Norway
From the 8th to the 10th century, the wider Scandinavian region was the source of Vikings. The looting of the monastery at Lindisfarne in Northeast England in 793 by Norse people has long been regarded as the event which marked the beginning of the Viking Age. This age was characterised by expansion and emigration by Viking seafarers. They colonised, raided, and traded in all parts of Europe. Norwegian Viking explorers first discovered Iceland by accident in the 9th century when heading for the Faroe Islands, and eventually came across Vinland, known today as Newfoundland, in Canada. The Vikings from Norway were most active in the northern and western British Isles and eastern North America isles.
Ólchobar mac Cináeda
Late in 848 Ólchobar is said to have set up a camp from which the Vikings at Cork were blockaded. The result of this siege is nowhere recorded. This is the first mention of the Vikings at Cork. They are not heard of again until 865. It has been suggested that these several campaigns against Vikings were a coordinated effort by the chief Irish kings.