The area from Ireland and the Irish Sea in the south-west to Greenland in the north-west saw an extensive expansion of Norse settlement in the ninth and tenth centuries (cf. Chapter 5). Cultural contacts across the sea between Norway and the British Isles may have begun much earlier. On the basis of archaeological evidence it has been suggested that they had been established already in the Migration Period and that there were connections between Norway and Orkney in the seventh and eighth centuries. The earliest known Viking raids on the coasts of Britain and Ireland towards the end of the eighth century suggest that by then there were at least Norse pirate settlements in the Northern and Western Isles and a few Norse grave finds in the islands may possibly be older than 800. However, it appears that the westward expansion of settlement from Norway did not assume larger proportions until the mid-ninth century.

The number of emigrants in the following period was sufficient to establish largely Norse communities as far south as Ireland and the Isle of Man, while from Orkney northwards the Norse settlers achieved complete dominance. Here, and in the Hebrides too, they found natural conditions very like those with which they were familiar from the coastal districts of western Norway, the homeland of most of the settlers. But the opportunities for varying combinations of agriculture, animal husbandry, fowling, fishing, and hunting were in general probably better than in the Norwegian Vestlandet, where the reserves of new land to exploit were by then restricted.