In 1992 a severe storm exposed stone walls of an ancient village which had lain hidden under sand dunes at Bosta Beach. These included oval foundations from Pictish houses of the Iron Age and rectangular Viking foundations. This probably should not have been a surprise, since Bostadh means farm in Old Norse.
Vikings made boring pottery and not much metalwork was found at Bosta. The most interesting finds had to do with food, both animals and plants. Let's start with fish, because there was a major difference between the Viking period fish bones and those from the Pictish period. The Picts ate fish, but it was all caught close to shore. The Vikings, as you might expect, went much farther out to sea for their catches, and they also practiced net fishing of herring, which required the cooperation of several seagoing boats and dozens of people. This was another long-term impact they had on these islands, re-orienting them toward the Atlantic and in particular toward communal fishing.
Sheep, by contrast, were not killed until they were a year old, which is the normal pattern when people raise them for meat and wool. There were very few pig bones. The wild species included red deer (elk), gray seals, dolphins, otters, and a pine marten, the last two hunted for their fur.
How many Norsemen came to Lewis? Modern genetic studies suggest that about 22% of islanders' genes in the male lines come from Scandinavia, and 11% in the female lines. But that may not reflect the situation in the Viking Age; after all, the Scots reconquered the islands around eight hundred years ago, and we know of at least two waves of migration from the mainland to the outer islands, one in the 1740s. So in the year 1000 I suspect the number of Vikings was larger. The 2:1 ratio of male to female Norse is less than you see in many other violent conquests, so it seems that migration to the Hebrides was something of a family affair.
Graveyard on Barra, Outer Hebrides
But in their hearts, the men at least were people of the sea. Those surviving bits of Hebridean poetry are all about sailing, including a poem called "Gigantic Waves." They loved ships and boats. When they went to war, it was by ship; a lord's strength was measured in ships. When they wanted a contest, it was often a rowing race. The work that most captured their imaginations was at sea, daring the Atlantic in pursuit of fish, seals, and whales. Communities were built around herring fishing, and local leaders arose to lead these communal hunts. Their homes were built so they could look out at the ocean. Very often, they died at sea, for the Atlantic was not a forgiving place.