Imperial Byzantine mission made some progress in converting Persian aristocracy by the end of the 6
thcentury. Our sources on this matter are numerous, both Persian and Latin, narrative and fabulous. If we bring them all together and single out the historical core, we will see that this short‑lived success was the result of a typical political intrigue and did not involve active preaching. The first quarter of the 7thcentury witnessed impressive victories of emperor Heraclius in the Middle East and considerable spread of Byzantine Christianity — but it resembled a Crusade rather than a mission. Byzantines initiated the concept of «holy war», and all the conversions were made by force (a little later strong disgust at Greeks and their religion facilitated mass conversion to Islam in the Middle East). More interesting to us is the peaceful success among Christian princes of the Caucasus and Azerbaijan: as in Africa, political appeal of the Empire turns out to be more significant than the religious one.The propagation of Christianity in India, Central Asia and China was carried out by Nestorian missionaries who had nothing in common with Byzantium and were regarded as heretics by the imperial church. Arabic Christianity had no Greek roots, but when persecutions began, local Christians turned to Constantinople for help. Interestingly, Byzantium did not intervene but asked the Ethiopian king to do so. The source to which the author pays special attention is Vita of St. Grigentius, apostle of Himyarites (Southern Arabians). This text is of later origin, but it reflects some genuine facts and some general ideas, spread among Byzantines, of what a missionary should be like.