Or have they ever practiced a form of martial arts specific to their people?
Here is a response I provided earlier that has some video of a reconstruction of the "Stick Game" played by natives of Northern California. Wrestling and fighting were an integral aspect of the game.
Yea we played stickball still do but back then it was for solving disputes. It was thought of as a battle because people could be killed during the games. It's not as hardcore now but we still carve our own sticks