Mexican or Colonial Spanish Stirrup
 

I usually feel that most of these ascribed to be antique Chinese, Japanese, Spanish, etc., are usually fake, especially when they are made of brass, however, I believe this to be the real thing.
It is constructed of riveted sheet metal, encased in tooled leather.
I would guess that these are either Colonial Spanish or Mexican, circa 1850-1900.

Congrats, that's authentic Spanish Colonial. Probably Mexican.

Thanks; do you think I got the time frame correct?

Yes, I do. Second half of the 19th century, likely continuing a considerably older tradition.