The last kings of Norse America - Recorded radioshow

1362 memorial poem inscribed on the Spirit Pond runestone, found on the coast of Maine in 1971. This translation climaxed a decade of historical investigations by authors Johnson and Westin in which they address a 450 year-gap in North American history between the 1492 voyage of Columbus and the Vinland voyages of Leif Eriksson and Thorfinn Karlsefni shortly after 1000 ad.
After the Vinland voyages the Greenlanders developed a lucrative trade in North American furs, marketed in Norway and taxed by the king. But after 1300 a cooling climate caused the Green­land merchants to migrate to North America and the trade died.
To regain the trade and expand his empire, in 1356 King Magnus of Norway and Sweden sent his son, young King Haakon VI, on an expedition to North America with Commander Paul Knutson. The inscrip­tions on the Spirit Pond and Kensington runestones enable the authors to reconstruct the fascinating story of Magnus and his expedition, more than a century before Columbus left the shores of Spain.

A book about this:
https://www.amazon.com/Last-Kings-Norse-America-Runestone/dp/1592984193