The only info known about this person is the name written on the photo. Anyone have any ideas?

This is what the seller said about it:

"Here is a really great tintype photo from the 1860s of a wild and wooly looking young man. What is so great about this image is that the mans name is inscribed on the surface of the plate. William M. Watson (Wm. M. Watson) This is a 9th plate in half case, the lid is missing. The man looks to be at least part Cherokee. The shirt he is wearing underneath his coat is very interesting as it has rows of round zouave type buttons running along the very loose neck. He just screams Confederate to me, but that is just my thoughts. The over coat he is wearing does not appear to be military issue. As you can see there is some polarization to the plate, which give it an interesting look but doesn't detract from it's overall appearance. There is a slight scratch above his head. I found this wonderful photo in an old Tulsa Oklahoma estate."

Ken