Council of Seleucia-Ctesiphon

The Council of Seleucia-Ctesiphon, also called the Council of Mar Isaac, met in AD 410 in Seleucia-Ctesiphon, the capital of the Persian Sasanian Empire. Convened by King Yazdegerd I (399–421), it organized the Christians of his empire into a single structured church, which became known as the Church of the East.