There may be something more to be gained by analyzing Chief Joseph’s story about how his family came by the tablet. Joseph’s story of how his ancestors came by the tablet echoes the legends told in both North and South America about white culture-bringers. If in fact Joseph’s ancestors got the cuneiform tablet from the white visitors, it might be possible that the tablet provides a clue about where, and even when, the white visitors came from originally.
Cuneiform was the form of writing that was used in the Mesopotamian region from about 3,000 B.C. to roughly the beginning of the Common Era. Perhaps the tablet’s general age could be determined, which might in turn help to pinpoint the time of the visitor’s arrival among the ancestors of the Nez Perce chief. It might be worth a try . . .