Tibetan system Some skeptics have claimed that they are not authentic. Perhaps the most damning claim is that they do not even slightly resemble authentic Tibetan yoga. However, once I saw the exercises, I could immediately see that they show a distinct likeness to 'phrul 'khor exercises that I practiced. On the left are illustrations from a 1930s publication; on the right are illustrations of postures from the unquestionably authentic Tibetan system called _ rdo rje lus kyi ´phrul ´khor nyi zla kha sbyor_.