Greek East and Latin West

Greek East and Latin West are terms used to distinguish between the two parts of the Greco-Roman world and of medieval Christendom, specifically the eastern regions where Greek was the lingua franca (Greece, Anatolia, the southern Balkans, the Levant, and Egypt) and the western parts where Latin filled this role (Italy, Gaul, Hispania, North Africa, the northern Balkans, territories in Central Europe, and the British Isles).

[citation needed] At the start of late antiquity, beginning with the reorganization of the empire's provincial divisions during the reign of Diocletian (ruled 284–305), the concept of the Greek East developed to stand in contradistinction to the Latin West.

[3] Louth primarily attributed this purported 'transition from multi-cultural Byzantium to Greek East and Latin West [to] the rise of Islam and the Arab destruction of the stability of the Mediterranean world in the seventh century.

'[6] Nevertheless, the transition was a slow and complicated process with many factors rather than a single historic event, which 'set the two halves of Christianity on their gradually diverging tracks', as Byzantine literature professor Alexander Alexakis (2010) summarised Louth's analysis.

[7] These included observations that the Byzantine church-state dualism remained intact after the Western Roman Empire's collapse, while bishops and eventually the pope in the West sometimes wielded secular power, but the Carolingian monarchs' renovatio also promoted theological thought at a time when the pope was embroiled in worldly affairs (8th–9th century), that the Byzantine Iconoclasm controversy caused 'the first rift between Rome and Constantinople', and that the simultaneous missionary efforts to convert the Slavs led to a 'second point of contention between Rome and Constantinople', especially in Bulgaria (9th–10th century).