Tsering Shakya, author of The Dragon in the Land of Snows, is a highly regarded historian and scholar. His magnum opus is extremely well regarded in the field not because we're full of pro-Tibet, dreamy-eyed hippies, but because it's extremely well researched. He was born and grew up in a Tibet post-China, and saw that his reality as a Tibetan student living under Chinese rule didn't match the mandated education he received. He fled Tibet at one point and wanted to piece together the mystery of his country's origins because, if I remember correctly, he felt that the Tibetan stories he heard in exile didn't quite match up with what reality seemed to be either.

As a good and proper historian, he set about finding documentary evidence, and this is why TDitLoS is so highly regarded as a historical text: it is extremely well researched and has been pretty well-corroborated with evidence.

In fact, when I read it (admittedly the last time was a couple years ago, I keep looking at it again thinking I should reread it) I remember it being very friendly to the Chinese. Not that the Communist Party or the Beijing Government (or the People's Liberation Army, while we're at it) come out looking like roses, but that Shakya takes the time to show when the Tibetans acted foolishly, impulsively, or were not as heroic as the common story suggests, while he also admits that many changes the Chinese made in Tibet had beneficial effects. And he does so without saying, "Well on the other hand," as if he's trying to create some balance, but does so in an attempt (as any proper historian should do, IMO) to tell a full, clear, and objective story.

There's not a whole lot of simple answers. I feel pretty safe vouching for the Dalai Lama as a good source, I think there's some obvious and historical evidence that even as a young man leaving Tibet, he was interested in science, objectivity, and truth. But I think it's hard to call him an objective source by any stretch of the definition. After all, until he stepped down from temporal control of the Tibetan Government in Exile, he had the most to gain from an independent Tibet (i.e. a whole country).

It's actually for this reason that I absolutely hate one of the Western publishing industry's tendency to slap "Dalai Lama" on anything remotely related to Tibet. I like Thomas Laird's The Story of Tibet and think it's really well researched, but ultimately it is a series of conversations with the Dalai Lama, and its best purpose is to portray the common Tibetan understanding of history (reincarnation, emanation, and fusion with the supernatural world included and elaborated upon, as well). Alexander Norman's book The Secret Lives of the Dalai Lama (republished as Holders of the White Lotus) is the same - well researched, well written, etc. - but Norman has interviewed the Dalai Lama a couple of times, and His Holiness even wrote a foreward to Secret Lives. It helps add to the objectivity that the Lama even says that he disagrees with a lot of the points made in the book, but that it still serves as a useful and informative text even for Tibetans who sorely need the perspective.

The best general book on Tibetan history I can recommend is Sam van Schaik's Tibet: A History. He covers everything pre-1949, where Shakya is really focused on the last most controversial half-century of Tibetan history, but it's my two cents about it.

I'm probably going to regret this comparison, but sometimes I feel like trying to research this area is like being a historian who studies the Holocaust, but the only two sources are a camp guard and a victim. Obviously, the truth is not "somewhere in the middle" like how we treat a lot of history. It has to favor one or the other. But all of the history and documentation we can look into is corrupted by Mao and post-Mao propaganda.

Associations are hard to ignore. Tsering Shakya is a Tibetan researcher who works for Radio Free Asia. Another (Western) researcher who works for Radio Free Asia is Warren W. Smith who wrote Tibetan Nation and China's Tibet?: Autonomy or Assimilation. And while that association is difficult to ignore, those books are incredibly well researched and the books are an incredible exploration of Chinese foundation and justification for invading Tibet and their post-annexation propaganda campaign to the Tibetans, Chinese, and the rest of the world. Radio Free Asia association be damned.

At a certain point, history favors a point of view. And the mid-point between understanding and denying an atrocity is still denialism. We can talk about common Beijing talking points and how they fail on any semblance of logic (notice how history isn't even). But I'm not super interested in spreading Chinese talking points, even in the name of historical understanding.

Anyway, you'd be hard-pressed to find a Tibetan anywhere who will say that life was "perfect" before the Chinese came. Even the Dalai Lama's memoirs and histories acknowledge pre-Communist Tibet's many faults. And it's also worth noting that Tibet prior to the Chinese was more of an advanced tribal-confederation, not like a modern state. It's also worth noting that the current Dalai Lama was never in control of an independent Tibet. When he attained his majority and assumed the full responsibilities of his office in 1954, Tibet was already under the control of the PRC.

Aside from all that, this is the most common Tibet-related question on r/AH: 1, 2, 3, 4, 5, and 6.