The one thing I cheated on when I wrote Saving the Unicorn's Horn was the Vikings' discovery of Greenland.
Greenland is where narwhals live, so it's where the 'unicorn' horn would have come from. But these tusks probably wouldn't have been brought back to Europe until the Vikings actually settled in Greenland in 982, nearly 60 years after my story takes place. Lucy's grandfather is supposed to have brought the horn back with him, which would make the setting of my story almost 100 years too early for King Sigtryggr's death. (I did confess to this in a note at the front of the book, but if you've read the book, I bet you skipped that bit!)
Medieval portrait of Erik the Red - not what we think of these days as a typical Viking!
Anyway, the first permanent settler in Greenland was Erik the Red, who was probably nicknamed for his red hair. Before you assume that he was a noble and intrepid explorer though, you might bear in mind that the reason he sailed off to Greenland at all was that he was exiled from Iceland for killing people! (This nasty habit clearly ran in the family - Erik's parents had landed up in Iceland because Erik's father had killed someone in Norway and they'd all been exiled from there!)
So in 982, Erik sailed off to a land that other Vikings had found but failed to make a home in. The Saga of Erik the Red tells us that Erik spent all three years of his exile exploring this land. When he was allowed to come back to Iceland, he told stories of a country he called 'Greenland'. In fact, Greenland was very similar to Iceland, but Erik thought 'green' sounded more inviting than 'ice'. (I agree, don't you?) So he deliberately gave the country a nicer name to try and get people to go there. Whoever thought advertising was a modern phenomenon?
It worked, and in 985 Erik returned to Greenland with lots of other Vikings, and made two permanent settlements. Erik became 'Paramount Chieftain of Greenland' and was greatly respected and wealthy - quite a turn-around from being an exiled murderer! I can only imagine he must have been quite persuasive once he put the axe down!