As we all know, history is not an objective science free from the prejudices of man, and the history of Tibetan Buddhism, like that of Tibet itself, is likely not as simple as Ismene is leading some to believe. There are many scholars and human rights activists that strongly disagree with the research and interpretation presented by Parenti, et al.
From what I understand about modern Buddhism, and going back to the pure beliefs of the Buddha himself, truth is the most important thing. Buddhism is not a religion and will drop any tenet proven by modern science to be false. There is a lot of information for everyone to decide for oneself. Below is one snippet from the web, but there are plenty of books and research from all sides.
This is by far one of the most detailed examinations of Parenti's views on Tibet:
A Lie Repeated - The Far Left’s Flawed History of Tibet
By Joshua Michael Schrei
[snip]
In his writing on Tibet, Parenti shares something in common with all of his predecessors -Anna Louise Strong, A. Tom Grunfeld, and Roma and Stuart
Gelder among them- in that his writing on Tibet is essentially argumentative. He is not writing in order to give an unbiased history of a nation, he is writing in order to prove a point. In this case, the point he is trying to prove is that the society of 'old Tibet' was a terrible place, and that the resistance movement that is so visible today is essentially a movement to re-establish this despicable regime.
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In his descriptions of old Tibet, Parenti predominantly draws on the work of four historians - Anna Louise Strong, A. Tom Grunfeld, and Roma and Stuart Gelder. The fact that all of these historians had a romantic predilection towards Maoism and drew mostly on Chinese government statistics should surely be cause for concern as far as their legitimacy as source material. One certainly wouldn't trust the Indonesian government's party line on Aceh or East Timor. Or, for that matter, the U.S. government's continued assertion that the Iraqi people welcome the current American occupation. Such manipulations of public sentiment, in which an occupation is presented as 'the will of the people,' are – as a rule – only employed to further the agenda of the occupier.
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For the most part, Parenti and the handful of historians who have adopted the view of old Tibet as a despotic feudal theocracy have had little if no contact with actual Tibetans either in or outside Tibet. Therefore, they have no real way of gauging the sentiments of the Tibetan people. Neither Parenti, Strong, Grunfeld, nor the Gelders speak Tibetan - or Chinese for that matter- so the body of historical literature on the Tibet issue that is available to them is extremely limited. Tom Grunfeld never went to Tibet until after his book was published. Anna Louise Strong – a diehard Marxist – was given a tightly monitored Chinese government tour of Lhasa and then went on to proclaim that "a million Tibetan serfs have stood up! They are burying the old serfdom and building a new tomorrow!" One might say that one doesn't need to go to Paris to know the Eiffel tower exists. However, before dismissing an entire culture's history as despotically repressive it is perhaps worth speaking to a few of its representatives.
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Parenti does little better in his treatment of history, erroneously stating that the first Dalai Lama was installed by 'the Chinese army'. One would presume that a Yale Ph.D. would know the difference between Chinese and Mongols. But apparently, in the Parenti-Grunfeld-Strong school of history, one word is as good as another and a Chinese is as good as a Mongol, as long as the point gets across.
http://free-tibet.tribe.net/thread/620ccde6-66e7-4147-b078-d2115d323448