You'd probably be better off posting this in /r/AskAnthropology since it falls squarely in the realm of pre-history. The thing to bear in mind though is how slowly these migrations are taking place. A story of how, "we made an epic 500-mile trek" would be something worth preserving in a group's oral history. But a story of how, "the group across the river started encroaching on our hunting grounds so we moved twenty miles into the next valley"... not so much.

I can't speak to Native Americans, but I can say a bit about the use of oral histories to document pre-historic events. A [2014 study on oral histories of Aboriginal Australians] (http://research.usc.edu.au/vital/access/manager/Repository/usc:14264?queryType=vitalDismax&query=indigenous+australian+stories) found that lots of disparate local groups recorded stories of a [great flood that severed islands from the mainland] (http://theconversation.com/ancient-aboriginal-stories-preserve-history-of-a-rise-in-sea-level-36010). These stories are corroborated by previous work showing that the sea level around the Australian coast used to be ~120 meters lower than it is now, and that this change occurred around [6000-7000 years ago.] (http://theconversation.com/ancient-aboriginal-stories-preserve-history-of-a-rise-in-sea-level-36010)