I have checked through the posts and I do not see any references
to evidence that Roman Mithraism reached Japan or China. I've been
following this list for over a year or so...did I miss it? The forum
discussion mentioned Roman coins in China and I found something about
lost Roman soldiers of Crassus, but no archeological evidence of the
Mithras cult in China or Japan. The Mithraic group in Japan
( Pattie here...inserting linkage... http://home2.highway..._of_Mithra.html and http://homepage2.nif...n_Theology.html and finally http://home2.highway...at/magimenu.htm ) seems to
be a synthesis of Persian and Roman Mithraism and Buddhism, but do
not give any concrete information to support their claim that
Mithras reached Japan. There are references to "Miroku", the
Japanese name for Maitreya, (http://en.wikipedia.org/wiki/Maitreya )
but this doesn't really have anything to
do with Roman or Persian Mithraism.
Maitreya has similar characteristics to Mitra etymologically,
but developed separately from the Mithra of Persia and Mithras of
Rome as specific to Buddhism. The similarities in characteristics is
"Vairocana" is the Solar Buddha and the wiki article says that
the word does have its origin in Sanskrit from the Rig Veda itself
and "has the connotation to mean a brilliant, luminous sun". In
Japanese, Vairocana is called "Dainichi". "Dai" meaning "great"
and "nichi" meaning "day" or "sun". Actually, "taiyo" means sun but
it depends on the kanji used and in this case the combination of
characters for "Dainichi" apparently means "great sun". Dainichi is
the Buddha venerated by the Shingon sect which was founded by a
Japanese monk in the 9th century who learned tantric teachings in
Tibet and brought it back to Japan. So, no Roman or Persian Mithraic
connection there. The Solar Buddha of Tibet was probably derived
from India (since Bon was originally the native religion of Tibet,
not Buddhism), but it would have been a school that developed from
Sankrit origin and not Avestan.
The Japanese Mithraic group claims that Mithraism came over to
Japan from China via Korea, through "Shugendo". Ironically, I have
some knowledge of Shugendo and it is a slim possibility because the
Shugenja were wandering practitioners that in the beginning picked up
whatever religious influences were around like: Taoism, Buddhism, and
Shinto. But, Shugendo began in Japan as syncretism of all the
religious elements present at the time, not Korea or China. I admit
though that I have never seen any traces of Roman or Persian
Mithraism in Shugendo in my experience, though they do have esoteric
practices which are still secret. Unfortunately, as I understand it,
the Shugenja were forced to integrate into the Buddhist sects of
Shingon and Tendai by the warlords who wanted to keep an eye on them,
which altered the original form of "wandering monks" and perhaps lost
its Mithraic elements, if there were any. It appears to me that this
Japanese group most likely equates Mithra and Maitreya and claims
that Mithraism entered Japan that way.
I would like to believe that Roman or Persian Mithraism reached
Japan but I don't see it so far. If it did reach the east, then it
would likely be in India or the Himalayan region from ancient Persian
I would like to begin this by saying that I am 99.99999% certain that no form of Mithraism entered Japan during early times. Though the Mithra/Maitreya/Miroku link seems dubious, a lot of interesting strides are being made in terms of Proto-Indo-European languages and it's impossible for me to say whether or not this is a valid comparison. I will say that it's completely useless to attempt to bridge Mitra and Miroku since Miroku is derived directly from the Chinese Mile, which in turn is derived directly from the Sanskrit Maitreya. If this bridge is to be made, it must occur between the terms in the correct order.
As far as the Shugendo link is concerned, I find that dubious at best. Japan has many solar deities, the most central being Amaterasu, the sun goddess (well before the introduction of the Great Sun Buddha Dainichi Nyorai). However, if you look at almost any culture (even China has some squirreled away if you know where to look...), there are solar deities worshiped from early times. Just because Mitra is a solar deity doesn't mean that he is the basis for all solar deities in the Asian landmass. China's solar deities are far older than the Romans themselves (not to mention their gods) and if Japan's solar deities were imported, I think it'd make far more sense to incorporate closer deities.
Shugendo being a "combinatory" religion has caused many people to misinterpret what exactly it did. This fact is being misconstrued to imply possibilities (e.g. Mithra) where none should exist. I think this Japanese group is simply a modern group of people who like Mithra and start a group based around him since Mithra is rather esoteric relatively speaking from Japan. It's kind of like the groups in Japan who claim they are descended from one of the Lost Tribes of Israel. It's not provable by any means whatsoever, and regardless of how steadfastly anyone believes it, at the end of the day, it's still hokey.
By the way, a few corrections to the quote above: Dainichi Nyorai is the Japanese form for the Indian Buddhist deity Mahavairocana, the cosmic buddha. Dainichi Nyorai only gets the "great sun" aspect in Japan because of an attempt to equate him with Amaterasu. The Buddhist monk Kukai who brought Mahavairocana to Japan never studied in Tibet -- only in China. Nothing about Tibet or Bon really has anything to do with the Tantric Buddhism of China and Japan; they are two extremely different types of Tantric Buddhism.
I hope this helps. If you want more information on what I've volunteered here, feel free to e-mail me at yoshiaki.abe at gmail dot com. I don't check this list very frequently.
-- Yoshiaki Abe
P.S. -- I am also interested in Zoroastrianism entering China before the Tang. If anyone has any information on this, please share. :-)