The Secret History of the North
An article in The Guardian posits that a Amerindian woman was taken to Iceland in the 11th century. Based on DNA research, there are an estimated 80 living descendants in Iceland today. As recently as 1960, before the discovery of an Norse settlement at L'Anse aux Meadows, any pre-Columbian contact between Europeans and North Americans was discounted in academic circles. Current research gives evidence of many Viking-era settlements in Greenland, along with contemporary accounts given by Guðríðr Þorbjarnardóttir and chronicles from the sagas. Numerous Viking era artifacts have turned up in Inuit villages. The list of discoveries grows longer and longer as the years go by.
Why this trans-oceanic activity diminished is a fascinating subject- with epidemics, climate change, the Reformation, and economic/political warfare in Scandinavia all playing a part.