The land of silk exists. Ptolemy knew about it. Alexander knew. There's a sourcebook for Persia coming out, and it pretty much borders. Let's talk about it.
India, IMO, folds in neatly because of its shared Indo-European heritage. Except instead of Aesir and Vanir, Olympian and Titan, we have Asura and Deva. Interestingly, in India, the Devas (masters of natural forces, magic realm) are more respected than the Asura (masters of human dealings, fairy realm). There's an entire saga in that disjunct alone.
Buddhism is nominally monist, and The Church (the sourcebook, that is) lumps monistic mysticism with the Divine. Zen/Chan Buddhism is definitely monist, and is already an old religion by 1220 (although calling anything paradigm this far away from Europe is rather silly.) However, other branches of Buddhism have significant syncretism with Hinduism, and there's always Greco-Buddhism to consider (which has been brought up before), so fairy and magic Buddhists seem plausible too.
Shinto has a Realm War parallel in that Susano-wo ruled the earth for generations, before being pushed aside by Amaterasu. Assigning Magic to Susano-wo and Fairy to Amaterasu would be in keeping with 5th edition's cosmogony. Or reverse the assignment if you want to align them more with India.
Taoism is monist/divine again, but geomancy/feng shui seems to be magic, based as it is on an indifferent topography. Chinese folk deities are mostly fairy, as the celestial bureaucracy couldn't be more human-mimicking. I haven't the foggiest what to make of Confucianism, it's the most mundane "religion" I've ever seen, in more ways than one.
And to be honest, that's where the fun runs out for me, because there are no more parallels to draw. We could talk about what kind of powers they have and such but then it's no longer Ars Magica. I mean, they don't recognize Air as an element, and they think metal isn't Earth. Savages. (and yes, I'm purposely misinterpreting the five elements)