The medieval chronicles, set down on yellowed calf vellum eight centuries ago, describe Scotland – or Skotland, as it was known – as an unwelcome and inhospitable country offering rewards only to the bold.
"Icelanders who want to practise robbery are advised to go there," says one saga. "But it may cost them their life."
Another saga tells the story of Icelandic merchants who sailed into a west coast sea loch where they met 13 ships bristling with what they called "Vikings" – more an occupation than a nationality – but were actually natives.
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A Scot identified in the saga as Grjotgard, a kinsman of Melkolf, king of Scotland (Malcolm II), told them: "You have two choices. You can go ashore and we will take all your property, or we'll attack you and kill every man we lay our hands on." The merchants were terrified, the saga says, but presumably lived to tell their tale.
The chronicles have been interpreted by Gisli Sigurdsson, a historian at Reykjavik University, who believes the sagas – part fiction, part fact – reveal how the ancient Norse were far from the fearless pirates of legend.
As the Norsemen became as keen on trade as marauding, they were particularly nervous about sailing up the west coast sea lochs they referred to as the "Scottish fjords". "The only places the Norse could have expected a safe reception was Orkney and Shetland, where the people were basically the same as them and where they would be greeted as kin," Mr Sigurdsson said.
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The Norse Viking age peaked between the 9th and 12th centuries, when Scandinavian seafarers conquered new lands, settling Orkney, Shetland, Iceland and Greenland, and establishing colonies in Scotland, England, Ireland, France, North America and Russia.
The Icelandic sagas, written in the 13th century but based on earlier oral stories, were often used as route guides for raiders, traders, crusaders and explorers, effectively a road map of medieval Europe and the Middle East. They have proved remarkably accurate, even helping archaeologists to pinpoint the remains of a Norse village in Newfoundland.
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Orkney is described as a handy base camp for pillaging Scotland. But the Norse had other bases too, some of which would feature high up in a modern guide for tourists. If you are planning to raid Scotland, one saga reads, you could do worse than base yourself in Fort Skardaborg. That's today's Scarborough.
Mr Sigurdsson believes the Norse Vikings were particularly nervous about the Gaels of Ireland and west Scotland.
Orkney historian Tom Muir said: "They picked weak targets, like monasteries. Some of the monasteries were basically unguarded banks of cash with a sign above them saying 'free money'. The truth is that there were raids both ways and that the Norse had every reason to fear their Celtic neighbours. There are well-documented accounts of Gaelic-speaking Lewismen raiding Orkney."
The Norse eventually lost their hold in Scotland. But Celts and the Vikings must ultimately have started to get along. DNA evidence suggests many Scots and Icelanders interbred and settled in both countries.