1. To assume an ancient culture located in a savage land, which also at one point had an extensive EMPIRE, never developed fighting arts is silly on the face of it
2. history of course teaches us about the hoseman warriors, their skills with knives, swords and spears. These same warriors rode into battle against Chinese tanks during the invasion and got decimated, but that doesn't mean they didn't exist
3. A prominent Shaolin Lo Han instructor who I know has worked out with the monks who are the Dalai Lama's bodyguards. The martial art they practice is considered a national security secret, ie better for people to assume he is not protected
4. In a famous German account of Tibet before the invasion, they refer to an inner monastery martial art which, surprisingly, has movements based upon the famous scenes fo Buddhist imagry
5. I have a student who is married to a Tibetan and lived in Northern India in the exile community. He saw plenty of martial art
I could go on, but of course, because YOU say so, it can't possibly be true