Although the significant cultural-geographical regions can be determined by various distinctive features, my aim is to demarcate the Ortodox region by synthesising the conclusions of historians (civilization and church history) and geographers (primarily cultural geography) in the present paper. From the geographical point of view, it facilitates the examination that the natural borders of Asia in the North and in the East (the Arctic Ocean and the North Pacific Ocean) can be interpreted as civilization borders as well. However, the situation is more complex in the West and in the South, as thousand-year-old cultures, religions and ethnicities mingle which obscures the boundaries of the studied region. By analysing historical and theological/religious aspects, the most important events in the first millennium of Christianity are discussed in order to demonstrate how unmistakably the regional differences have manifested in the history of Eastern Christianity. The analysis of cultural, historical, political and geographical characteristics is going to reveal the similarities and/or discrepancies between the Ortodoxy and the neighbouring civilizations.