I was very interested to see your request for information on Dabeichuan.  I was under the impression nobody in the US had even heard of it, even it they only knew the name and nothing else.  I studied Dabeichuan when I was living in Beijing from 1998-99 and 2001.  While I don’t know very much about it, I’d be happy to share the extent of my knowledge with you.

    At first my teacher introduced it to me as “The most esoteric form of Shaolin.”  As far as he knew there are only a handful of people teaching Dabeichuan in Beijing.  He’s pretty well connected in the Beijing martial arts scene, so I took that as being more or less true.  However, I have seen a book on the subject in his master’s house, so it is at least somewhat known.  It was brought to Beijing by a Shaolin monk in the late 50s.  He taught a handful of students before he was murdered by red guards during the Cultural Revolution, although how a group of teenagers could take out a Shaolin monk is beyond me, probably just shot him in his sleep like good little fanatics.

     All told there are 5 or 6 students of his, or students of students that teach it in Beijing, and three Americans that I know of who have studied it.  One of his student made his own version of it that is shorter, but includes moves that are a lot more difficult to do (as in physically challenging, not necessarily complex).  There’s also a dabei staff, which is even more obscure, but I’ve never seen it.

    The full name of it is DaBeiTuoluoni Chuan, which translates into “Occult Mantra of Great Compassion Boxing.”  It is a Tantric Buddhist style which is associated with a sutra, the “Occult Mantra of Great Compassion Scripture” Dabetuoluoni Jing.  Tuoluoni is the translation of a Sanskrit word that I’ve forgotten which is a secret mantra which gives you occult powers when you recite it, a common Tantric practice.  The form gets its name because you are supposed to chant the scripture while you do it.  In order to avoid persecution during the Cultural Revolution the name was changed variously to DabeiChuan ChanChuan (meditation boxing, the same word as Zen Buddhism) Bei Chuan, etc.  The fact that it is Tantric is somewhat interesting, because Tantric Buddhism was supposed to have passed through China in the 800s without making any impact whatsoever before disappearing.  Indeed, indeed that’s the only statement about tantrism that any book on the history of Chinese Buddhism seems to have.  I asked my teacher about this and he just said, “Why do you think they call it tantric (mizong - literally secret doctrine)

    The actual form consists of about 210 movements it two circuits (lu).  It is slow moving and looks rather like taiji, except for the fact that it moves in straight lines and has points where you hold mudras.  Its good at working all of the muscle groups that shaolin and taiji miss.  My teacher originally taught me to do it stretching out your arms at several points, which is consistent with chanmigong, a Tantric/Taoist hybrid form of qigong.

    Like taiji, it is also a very effective form of qigong.  However, the feeling that it gives you after practicing it is completely different in a way that I can’t really describe. While taiji gives you feelings of warmth and energy flow along your meridians, Beichuan just makes you feel empty.  My teacher told me that you shouldn’t practice it and other Taoist forms of qigong in a row or it will screw you up…

    And that’s all I can really think of.  As for whether or not it’s a “legitimate internal martial art style”, as you put it, I wouldn’t be the one to ask.  I’m generally of the opinion that how internal/external an art is rests in the practitioner and not in the art itself.  That said, its an art in which 80 year old men can easily do things with their body that I couldn't do at 20, which is the best litmus test for an internal art that I’ve come up with.

Hope that helps.

 Peter