Church of the East

The Church of the East (Classical Syriac: ܥܕܬܐ ܕܡܕܢܚܐ ʿĒḏtā d-Maḏenḥā) or the East Syriac Church, also called the Church of Seleucia-Ctesiphon, the Persian Church, the Assyrian Church, the Babylonian Church, or the Nestorian Church, is one of three major branches of Eastern Nicene Christianity that arose from the Christological controversies in the 5th century and the 6th century, alongside that of Miaphysitism (which came to be known as the Oriental Orthodox Churches) and Chalcedonian Christianity (from which Catholicism, Eastern Orthodoxy and Protestantism would arise). Not to be confused with, The Maphrianate of the East at Tigris (Also known as the Catholicate of the East to counter the Nestorian Catholicate) which was established in 628–629 AD as the ecclesiastical headquarters for the Syriac Orthodox Church (Jacobite) within the Persian Empire, separate from the Church of the East. Centered in Tagrit (modern-day Iraq) on the Tigris River, the Maphrian held the second-highest rank after the Patriarch of Antioch, ruling until the seat moved to Mosul and presently located in India.

Having its origins in Mesopotamia during the time of the Parthian Empire, the Church of the East developed its own unique form of Christian theology and liturgy. During the early modern period, a series of schisms gave rise to rival patriarchates, sometimes two, sometimes three. In the latter half of the 20th century, the traditionalist patriarchate of the church underwent a split into two rival patriarchates, namely the Assyrian Church of the East and the Ancient Church of the East, which continue to follow the traditional theology and liturgy of the mother church. The Chaldean Catholic Church based in Iraq and the Syro-Malabar Church in India are two Eastern Catholic churches which also claim the heritage of the Church of the East.