MMA is nothing more than training methodology. The arts involved can be any arts. Its whether or not they can be pressure tested and used efficiently under this pressure.

Also, the focus is on more than one range of fighting. It isnt just striking or just grappling, its the use of striking clinch and ground ranges. The reason that MOST mma is Boxing and BJJ is because that has been found to be the best skill set to work with in a COMPETITION setting.

The truth is MMA has existed much longer than the term MMA, the idea is not new, it simply got brought to the limelight with the advent of venues such as the UFC.
"When I let Go of who I am, I become who I might be."
Lao Tzu