Alright Ken, i was influenced by the auction catalogue, as i already had of these bull "drivers" (don't remember the actual name); but now with the corrected weight i reckon it is bit too heavy for a bull to wander around with
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Then you come up with these bracelets that were more currency units than actual bracelets; i guess your example's interior diameter wouldn't fit an adult's wrist and maybe not even an youngster's one.
There certainly are members around that know a great deal about these things.
Meanwhile if you browse on Tuareg bracelets, for one, you will find similar examples.