What were the main centers of chistianity in the east?

Eastern Christianity consists of the Christian traditions and churches that developed in the Middle East, Africa, Eastern Europe, Asia Minor, the Balkans, Southern India and parts of the Far East over several centuries. The term does not describe a single communion or religious denomination. Some Eastern churches have more in common historically and theologically with Western Christianity than with one another. The various Eastern churches do not normally refer to themselves as "Eastern", with the exception of the Assyrian Church of the East and its offshoots.