Originally posted by RobG Interesting - maybe there's just not enough evidence left behind. There's a lot that can be concluded from evidence on a site without writing, especially if there's human remains for analysis. There's also things like food scraps and what they tell - such as how the available food sources changed over time. Even pollen grain analysis.
Rob, there are hundreds of books written, detailed studies by universities and I have still not seen anything conclusive. Here is a petroglyph I took a photo of in Utah which was a major travel point for numerous tribal nations that crossed the area. This is their written word.