That I don't know. IMO and this is just a guess..I would say both, some techniques being home grown and others from other outside sources as a system was being developed. They had battles to win so I imagine they used whatever would work when $^&% hit the fan and it
really mattered.
http://www.case.edu/affil/tibet/tibetanMonks/monks.htm
There is some contact info, maybe we need a volunteer to email them with some questions. Maybe Dr. Goldstein would be willing to make at the least an educated guess based on his prior work.