system
Given the following post, respond as if you're commenting on Reddit:
human
[Back to the Future] What were Sioux warriors doing in California?

Or for that matter, what was a Plains Cavalry unit doing there?  In 1885 hostilities had ceased between the Sioux and the U.S.  They would resume again in a few years, but Marty would be long gone by then.

In any case, they were on the wrong side of the Rockies.  The indigenous people of California weren't horsemen and didn't wear the feathered war bonnets like the Great Plains Nations.
gpt
This is a common misunderstanding. The group Marty encountered were actually performers from Buffalo Bill's Wild West Show, engaged in a full dress rehearsal. They were understandably disconcerted by the appearance of a DeLorean right in front of them, and their following actions stemmed mostly from confusion and panic.