not being an expert i do seem to remember grandma saying those sorts of patterns had to do with the 4 winds. I would also say plains indians, and functional.
Do they have different leather for the soles? Early genuine mocs will have rawhide (untanned leather) with softer tanned uppers. Are the soles sewn on with thread or sinew? If the soles and sides are one piece they are not really old. I made my own mocs with one piece soles and sides, tops sewn on with thread and no rawhide soles when I was a kid and did better bead work than those.