The confusing thing for Native American ethnohistorians, is why did almost no North American peoples either develop or adopt written language?
Several Mesoamerican cultures developed it, apparently independently, and there was sufficient contact between the American Southwest and northern Mexico to make at least the Olmec and Aztec alphabets available to cultural exchange and exaptation. Yet not even the Kiowa, Zuñi, Hopi or Comanche have a written language of their own, even though each had archaeologically-established contacts with Mexico and the writing cultures there.
The ancient but hardly forgotten Mogollon had a trade-tally system of some sophistication, like the Inca, but it was in knots and beads, not writing. (also apparently independent; it is fairly unlikely that any Mogollon to make the 3,000-mile-plus journey to the Andes would ever have made it back to Arizona, and if they did, they left no obvious artifacts from South America behind)
The question, of course, is why not? Writing is a cultural “good idea,” the same kind of good idea as the bow and irrigation, that tend to spread rapidly and even nigh-simultaneously across cultural and political boundaries as soon as they appear, because of their obvious utility and universal applicability.
The modern Hopi and Apache, descendents of the mysterious Anasazi, the Navajo and Comanche and Mogollon, all have oral histories of one form or another, but nothing like (at least outwardly) the rigorous tale-memorization practiced in pre-literate southern or western Europe, where the new tale-keeper had to recite word for word hundreds of years of his ancestors' lineage, deeds, and law, for years before he (usually he) was accepted as the heir to the tribal wisdom and began to be consulted in favor of the old or dying prior poet. Native American tales are remembered, yes, but each teller has his or her own way of telling it, and at least in the Hopi tradition, each personal “spin” is the right one for that personal tale; the wisdom of telling is as important as the wisdom of the tale itself.
This could be a partial clue to why no writing: like noting down jazz, one loses the essential improvisational and contextual nature of the story, which has repeated themes and even events, but changes and reveals new things with each telling and each teller. It is not a recitation of a memorized work, so much as an extemporization on an established theme.
And of course, there are the Spanish and other Europeans, whose first contacts with Native Americans often either killed the people who knew the oldest tales, wrote down incomplete or culturally inaccurate versions of them (which of course, became the remembered version for everyone who had not heard the original form) or suppressed the language and culture from which those tales had sprung, dooming them to be simply forgotten under the duress of other events. Time does not stamp out cultures, but it unavoidably (in many cases gratefully) forces change, and part of that change is often that art, literature, music, and yes, stories, change, become outmoded and are no longer venerated or outright forgotten. Today's hero (Herakles, say) after whom many towns are named and shrines dedicated, becomes tomorrow's example of headstrong virility, and a thousand years from now's half-forgotten legend, only available in books and a few museums in backwater towns that no one from outside ever visits.
So perhaps a partial, shallow explanation for why we have no accurate histories of Native American peoples outside of the Mayan temple-writing (and who's to say those historiographies are anything other than lionized versions of contemporary politics) but the mystery remains, and the frustration, that the hundreds of cultures across central and North America especially, neither developed nor adapted writing to assist with their thinking, and our thinking about them.