Church of the East
In the fifth century, the church in Mesopotamia sided with Nestorius, the archbishop of Constantinople, whose views where condemned at the Council of Chalcedon (451) and as a result, like the Syriac Orthodox Church separated from the Syriac Orthodox Patriarchate of Antioch and thus broke relations with the Ecumenical Patriarchate and Roman Catholic Church. The Mesopotamian church became known as the Church of the East. A schism in the sixteenth century over the problem of succession of the Patriarch led to the formation of both the independent Assyrian Church of the East and the Chaldean Catholic Church (one of the Eastern Catholic churches in communion with Rome).