I knew it had gotten that far, was thinking more about significant population portions. But I guess it did get large amounts in all of Romes immediate neighbors Before the fallChristianity made it at least as far as China and India, though it was a minority religion there. Nestorian Christianity specifically was one of the big players in Central Asia alongside Buddhism and Manichaeism. Christianity also filtered into Persia and the Arabian tribes, and the Goths weren't pagan but Arian Christians. Plus Christianity made it to Sudan and Ethiopia very quickly. So Christianity got around--it's just that Rome dominated a big chunk of the world at the time.