I was going on what a poster said on one of these threads; he had an exact date, some time prior to 4,000 years ago. I don't remember it exactly.
But if I am going to look into old sites, I need a fairly specific target date. I have been in sites back to 10,000-11,000. They are more scarce than younger sites, and often have less material surviving.
I try to be civil, and I appreciate your reasoned approach as well.
But watch out, I might throw a little humor in now and again. Coyote is bringer of knowledge and culture to many western Indian groups, but also the trickster.