> ‘Prehistory’, like so many categories that we use to frame the past, is not only a convenient label, but a deeply problematic inheritance.
I'm all for learning everything we can from unwritten sources. The problem is that they're unwritten. Tools, coins, ruins ... all those survive and can be analyzed. But what you notice from the analyses of those is: they're pretty tenuous. Writers make inferences that are, well, open to question, but it's all they can do.
As for "oral cultures" : yes, absolutely, if they survive. But AFAIK no Native American culture has any legend on how they came over from Siberia, nor do Australian aborigines "remember" how they migrated from Asia and Indonesia. Yet we know that they did.