Professor was talking about the legal structure of Pre-Spanish America then rambled off about the other Native Americans in the North and commented that they fought against exploring Vikings, defeated their exploration parties and even drove them out of Greenland. Then he went on about how the few abandoned norsemen and their forgotten descendants that remained in Greenland, barely scrapped by and had a miserable existence there while also fighting a new different group that had come to the Americas thousands of years after the original native american settlers/inhabitants, through Alaska and expanded throughout the Artic region called Proto Eskimo/Inuit. This new group went on to expand in Greenland and exterminated the remaining norse colonies or mixed with them.
I had never heard anything about any of that. How accurate is it and what really happened with Viking/Norse explorations and settlements in North America and Greenland?
That's pretty accurate. The Dorset people were in modern Canada and the islands approaching Greenland from 500BC to about 1000AD. It's contested as to exactly when the Thule migrated but around 1000 their people crossed Canada and, by the 14th century, had become well established in Greenland. As for the Norse history entering the area, I recently wrote;
According to sagas written in the 13th/14th century, a ship was blown off course in about 985, discovering new land but not investigating it. Around 1000, Leif Eriksson sailed west to explore those lands; he named them Helluland, Markland, and Vinland (the islands and coastal bands of North America, likely Baffin's, Labrador, and Nova Scotia/New Brunswick). A few years later, his brother, Thorvald Eiriksson, went back. This is when first contact occured, with the Norsemen finding a drying structure while exploring. The next day they came across nine people sleeping under overturned canoes, so they killed them. Soon after they were attacked by what they called skraelings or something like "wretched shrieking people" in Norse. Thorvald would die there and the third brother, Thorstein would launch a failed expedition to retrieve his body. Thorstein later died of illness and his wife married Thorfinn Karlsefni who then took his family and attempted to settle in Vinland They had somewhat good relations despite the initial troubles and it is likely they were dealing with a different tribe than Thorvald had. They encountered one another in odd ways, the natives waving sticks and the Norse raising a white shield. It was an attempt to communicate and trade soon followed. What happened next is, according to some, a different tribe finding/learning of the Norse settlement and attacking, causing Thorfinn to return to Iceland and abandon the settlement. All we know comes from the sagas, so it is unclear exactly who attacked or why.
So there was definitely one group leaving as Leif came exploring. By the time his saga was actually written down, an entirely different culture had migrated and replaced them and ultimately moved further east than their predecessors.
Perhaps others can comment on the "extermination" of Greenland Vikings by natives.