Hi Battara,
Thank you for the update, I was hoping this thread wouldnt end.
Your observations sound right on, and as I had suggested this item probably was from plains tribes in the earlier period you note. As I noted, it is unlikely this would have come from the 'souvenier' period post Wild Bill
and this would indeed be an authentic piece......fantastic!
Thank you for pointing out the type of paint also. In more reading I discovered more on the painting being consistant with these also.
All best regards,
Jim