Two of these guys are showing us their sheaths:
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The image is from A.J. MIller, "Hunting Elk Among the Black Hills." Blow the picture up and you see a line of dots along the outer edge of each sheath. Tacks? Rivets?
This painting by Karl Bodmer has been shown here on the forum numerous times, but we keep coming back to it because there is so much to see:
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You can just see the throat of his sheath behind his back. It looks like it could be a rawhide sheath to me, laced with a double running stitch, judging from the two free ends of the lace that are showing. One thing we get from the two pictures (Miller and Bodmer) is that it must have been pretty common to wear the sheath behind the back, positioned with the cutting edge of the knife down and the knife handle accessible to the right hand.
This next sheath belonged to a Cheyenne man named Big Back, who was active in the Indian wars of the 1870's:
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This is a bit late for
@Smokey Plainsman 's period, but I don't think sheaths necessarily changed that much.
This Lakota sheath was dated to the 1860's. I think the "X" lacing is probably a later repair, as it is the only sheath I have seen laced that way, but who knows?:
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One more rather plain rawhide sheath, undated, with an extension to catch on the wearer's belt, as on the shooter in the Miller illustration (above):
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Based on the way the painted design is oriented, I think this one was probably made from a recycled parfleche.
There are lots of authentic options out there.
Best regards,
Notchy Bob