The collective term by which is designated the Churches which formerly made part of the Eastern Empire of Rome. The Greek, Russian, Coptic, Armenian, Syrian and other eastern churches are those usually included in this Communion. But in strictness, the term "Eastern" or "Oriental Church" is applied only to the Graeco-Russian Church in communion with the Patriarch of Constantinople. The great Schism whereby the communion between the East and the West was broken took place, A.D. 1054.