These are currently posted at Cowans. They're identified as Southern Cheyenne and a date in the 1870s is suggested; from the backdrop, five seem to come from the same studio. However, someone (Jinlian, I think) has already identified the man at the top left of the first group as Plenty Wolves/Yankton Charlie with his wife - and he looks a little older than in the Godkin portrait, so I guess they're dated early to mid 1880s and the subjects are presumably Lakota and/or Northern Cheyenne.
The man with the pocket watch is - I'm pretty sure - Young Spotted Tail.
The two underneath Charlie are clearly not from the same set. Omaha, perhaps? Likewise, the man with the breastplate in the second group possibly does not belong with the others and may be an earlier photo judging from the clothing and accessories.
Are they Cross photos from the early 80s? Anyone got any ideas? Ephriam?
I'm sure there's a way of obtaining a larger version of the picture from Cowans...