George S. Ledyard
So my point is that yes, I do believe that this stuff came from China. It may very well have come from India before that but I don't expect anyone to prove that either way. The Chinese manifested these principles in their martial arts as they fit their personal, social, political, technological and military context.
"This stuff" (meaning the so-called 'internal' skills) probably originated in India and spread gradually to China and from there to the area of influence China had as a dominant power. My personal suspicion is that "this stuff" originated (not whole, but gradually) as an adjunct to agrarian work necessities. Both the forces and "ki" skills are so suitable for work efficiency that I can easily picture them as being quasi-religious skills at a time when religions had a lot to do with planting, harvest, fertility, food production, and so forth.
Regardless, "this stuff", as physical skills, is an intertwined system of logic and physical phenomena in which one thing implies another. In other words, it is a stand-alone system of logic. There is not really a "Chinese system" and a "Japanese system" and a "DR system" and an "Aikido System" and a "Taiji system", or any of that. There is only one system. If there are differences, those differences represent different levels of understanding and ability... nothing more.
Yes, someone can devise his own system of techniques and apply any vouchsafed 'philosophy' of his choosing, and so on, but the system of logic and skills is immutable. That's one of the reasons why you see the same ki demonstrations (or their variations) all over Asia; ki skills are ultimately defined and limited by what they can do. Once you grasp the bigger picture of what is going on, this immutability becomes obvious.
Also, because of the way the system works, you begin to see some very simple and clear principles such as motion reducing to stillness, such as "form approaches no form", such as "my opponent moves first but I arrive first", and so on. The same simple principles that Ueshiba referred to in his douka. This system of body skills is not Chinese or Indian or Japanese or whatever... it simply is what it is and it is an important basis for what "Dao" is.