In the book a survey is made of Byzantine efforts to convert nomads. Greek sources here are numerous. For centuries Byzantines regarded nomads as essentially unlawful people whose conversion to Christianity demanded that they fully reject their basic ways of life. For example, the missionaries were trying to forbid Tatars to drink «koumys» (horse milk). But such rigidity gradually gave way to more sober approach: as the Empire was declining, its demands became less strict. It can be proved by the marginal notes in the «Sugdaian Synaxarion» and by such outstanding and largely overlooked source as the questions of Theognoste, the Greek bishop of Saray (capital of Tatars), addressed to Constantinopolitan patriarch John Bekkos, and the answers of the latter about the sense and the formalities of missionary practices. This is a document of real religious wisdom and tolerance. It proves that Greeks preached to nomads in difficult circumstances, and showed great courage in doing this. They simplified the rite, adjusted the teaching and tried hard to disseminate not the Byzantine way of life, but the most general concepts of Christianity. Interestingly, the Patriarch approves of all the innovations suggested by the bishop with the only exception: he insists on the excommunication of a priest who happened to kill somebody during his missionary service.