Thorfinn describes landing in North America and getting stranded seven winters (years) after the Battle of Svolder. This is a real battle fought in 1000 AD on the Baltic Sea, between King Olaf of Norway and a coalition of the Kings and of Sweden and Denmark, and the jarls of Norway.
Olaf sought to unify Norway under his rule. His Christian rule. After taking power from the "foreign" rulers, Olaf (who abandoned his English wife to return to Norway) began a campaign of murder and torture to convert the country to Christianity.
Mead is an alcoholic drink made from honey. First made in Africa around 20,000BC, it became popular all across Europe, often produced by monks.
It was traditionally used for celebrations, and is the origin of the term honeymoon.
Scandinavian couples would drink mead (honey) for an entire cycle of the moon after their wedding.