Buddhism as you and I understand it is way different from how it is perceived in other parts of Asia. I realized that several years ago when I visited a Buddhist temple here of Taiwanese heritage. For us, Buddha was a dude (as per legend) from whom Buddhism started. For them, that Buddha, called Siddharta Gautama or the Shakya Muni, is one in a line of many Buddhas before and after. So there was a lot of changes that probably happened as the religion traveled. The Tibetan Buddhist artifacts that I have seen in a museum here are what you mention - they are basically our devas and devis with different names, but those don't seem to show up in other parts of Asia.
Many people don't know that "Zen" is nothing but "Chan" which is nothing but the Sanskrit "Dhyan" which the Chinese found hard to pronounce.
You have the last part right. I think from
Dhyana it goes to
Jhana (which is the
prakrit or
pali term since the common man also found Sanskrit hard to pronounce and therefore the Buddha preferred to use Pali terms), and then to
Chan and finally
Zen.
It seems Buddhism evolved as it went, with two schools in China - the northern and the southern, one went for Instant Enlightenment and one for gradual. (I am enormously simplifying the whole thing, I read only a little long back). Those chaps fought a lot and even killed each other over becoming the head of their sect. I remember reading about the last or second last Patriarch in China. It's quite amazing for an Indian (even non-B) to read about these B monks killing each other to ascend to a position.
In Tibet, it seems they have added so much (
bardos and all kinds of stuff). They claim to have a lineage or descendancy (like avatars) so that they can increase their knowledge of death and beyond. This way they claim they know more than their predecessors since the knowledge is accumulating. They also are not interested in working for their enlightenment - since they feel they will not be able to help others if they are enlightened. They prefer to delay it and remain just on the edge.
However, the Buddha was enlightened so I don't see how that logic works. As far as He was concerned only an enlightened person could help others. He was careful in selecting his teachers who had to be
arahats.
That said, I do think that B'ism actually flourished in the far east more than in India. In India B'ism is just a hereditary religion not a true practice. There are no B'ist Masters in India to guide interested students. At least in China, Korea and Japan, one hears of Masters who passed down the actual practice, selected enlightened students to continue. Today, for example, we have Thich Nhat Hanh from the East (and many others who are not famous).
The
Vipassana (
Vipashyana in Skt.) that is taught today (founded by SK Goenka) is quite a modification even of the Burmese Master that he took from. And even that does not tally with the Buddha's own teachings. SK Goenka seems to have modified what he took from a Master, whereas he himself (SKG) was not enlightened and has/had some very funny theories of his own which completely undermine his credibility.
I would therefore
not consider Vipassana to reflect on the health of Buddhism in India or elsewhere.
