Complex sentence: The Greek East and Latin West are terms used to divide Christendom into the Greek-speaking, Orthodox peoples of the Eastern Mediterranean Sea, centered around the Byzantine Empire, and the Latin-speaking Catholic peoples of Western Europe.
Split into simpler sentences: The Greek East is a phrase used to define the territories of the Greek-speaking, Orthodox peoples of the Eastern Mediterranean Sea, centered around the Byzantine Empire. This is in contrast to the Latin-speaking Catholic peoples of Western Europe.