There is a so nice museum of indigenous people in Hokkaido, called "Sapporo Ainu Culture Center" that has various kinds of Ainu art and their philosophy.
Particularly, the design of patterns on their textile is worthwhile.
But you may find some similarities between these designs and the clothes on the Asian Continent.
On the other hand, when the army of Mr. Hideyoshi Toyotomi conquered Korean Peninsula, the front line of the cavalry was devastated by a female horse because the horses of Toyotomi's cavalry were not castrated albeit that should be done before the war. That was the common sense for the tribe of cavalry. If the origin of the current Japanese was the tribe that has cavalry, the "must-do" was done at that time, the opposite said.
It is very interesting and actually we can find some similarities between them but I am not sure at this moment.