How far back will you take your POD? I don't think Tang dynasty influence can flow much farther West than it did. The costs were huge as it was.
One thing I think would be interesting would be a strongly proselytising form of Buddhism emerging from China. The Northern Wei might make a good candidate for that. With a 200-odd year head start on Islam, Chinese scriptures and a high civilisation to push it, that could easily reach the shores of the Black Sea and even push into Eastern and Central Europe. Not exactly Sinosphere, but if powerful Khazars, Bulgars and Avars more or less regularly set out on pilgrimages to Shaolin monastery, awareness and cultural influence will be much stronger.