<P> Koine Greek had become a shared language around the eastern Mediterranean and into Asia Minor as a consequence of the conquests of Alexander the Great . The `` linguistic frontier '' dividing the Latin West and the Greek East passed through the Balkan peninsula . Educated Romans , particularly those of the ruling elite , studied and often achieved a high degree of fluency in Greek , which was useful for diplomatic communications in the East even beyond the borders of the Empire . The international use of Greek was one condition that enabled the spread of Christianity , as indicated for example by the choice of Greek as the language of the Epistles of Paul and its use for the ecumenical councils of the Christian Roman Empire . With the dissolution of the Empire in the West , Greek became the dominant language of the Eastern Roman Empire , later known as the Byzantine Empire . </P>
the most common language in the eastern mediterranean during the height of the roman empire was
Koine Greek