I was wondering about how a different Vinland colonization scenario might affect the new New World.
What if instead of lasting 10 years and being highly-halfhearted, the Viking settlement was actively attempted and lasted closer to 60 or a 100 years, but still eventually was given up? A longer time period of colonization would mean that the Vikings would bring at least some horses and cattle to the New World, and when they gave up the colony, it is very likely that some of the horses and cattle would be passed to the Indian tribes, if the local Native Americans hadn't bought them already.
Therefore, 400 years before Columbus or someone Columbus-esque, horses and cattle are rapidly spreading throughout the New World at the same rate they did OTL. What effect would this have on Native American societies, especially considering they could utilize the new animals while not being dragged down by smallpox and European attacks and encroachment? How much more difficult would later European colonization attempts be?