Early Roman medicine was a mixture of religion and witchcraft, but as time went by, it became more influenced by the Greek medical sciences, which were more developed. The most famous Greek physician during the Roman period was Galen (129-200 AD). In the 4th century A. D. The Byzantine physicians of the Emperor Julian, made the Galenic writings available to ordinary practitioners, and so Greek medicine spread throughout Syria and was carried by the Nestorians into Persia, where it became available to the Islamic World.