By the second Christian century Iraq claims Christian converts from paganism who wrote in Syriac and Greek. By the third century we have evidence of an organized community with an Episcopal  structure and church buildings.

During the fourth century, the land of Iraq witnessed a fierce persecutions of the Christians by the ruling Persians that claimed thousands of lives. Since it lasted forty years it is commonly called ‘The Forty Years Persecution’ (AD339-379).

During the fifth century two important synods were convened. The first was convened in AD 410 with the permission of the Persian ruler Yezdegird I, who officially recognized the Christian community and gave them rights of worship. The second Synod was convened in AD424 in which the Church within the Persian Empire severed all relations with the Western Church thus becoming self-ruling, with the bishop of the capital as the leader and final judge.

This church was sometimes called ‘The Persian Church’, ’The Nestorian Church’ or more correctly ‘The Church of the East’. From its centre, the capital of the Persian Empire Seleucia Ctesiphon, the Patriarch sent missions eastwards to Iran, Central Asia, India, China, and southwards to the Arabian Peninsula and Socotra.