This was probably taken in late 1880s-early 1890s:
Plenty Coups is sitting on the right in the group in the middle; the man kneeling of the left is policeman Fire Bear (who, among other things, killed Sword Bearer); the man on the far left looks like Spotted Horse; haven't managed so far to identified the man sitting near Plenty Coups (with headdress)-
Detail with Plenty Coups:
More and more to come...
"Don't ever tell anybody anything. If you do, you start missing everybody."