Nestorian Church of Persia

Church of the East
Syriac: ܥܕܬܐ ܕܡܕܢܚܐ‎
Ruins of the ancient city and See of Assur.
Classification	Eastern Christian
Orientation	Syriac Christian
Theology	Nestorianism
Head	Catholicos-Patriarchs of the East
Region	Middle East, South India, Far East
Liturgy	East Syrian Rite
Headquarters	Assur (Ottoman Empire)
Founder	Saint Thomas the Apostle, by its tradition
Origin	Apostolic Age, Nestorian Schism (431–544) Sasanian Empire
Separations	In 1552, divided into: branch united with the Catholic Church and independent branch centered in Alqosh
Other name(s)	Nestorian Church

The Church of the East (Syriac: ܥܕܬܐ ܕܡܕܢܚܐ‎ Ēdṯāʾ d-Maḏenḥā), also known as the Nestorian Church, was an Eastern Christian Church originating during the late 1st century AD in Assyria, then the satrapy of Assuristan in the Parthian Empire, before spreading to other parts of Asia during the late antiquity period and throughout the middle ages. It originated as an eastern branch of Syriac Christianity, and used the East Syrian Rite in liturgy. It developed distinctive theological and ecclesiological traditions, and played a major role in the history of Christianity in Asia. Its Schism of 1552 led to a series of internal divisions among Assyrian Christians during the early modern period, and ultimately branched into the Chaldean Catholic Church and the Assyrian Church of the East, the latter of which remained a continuation of the original church. The Ancient Church of the East trace their roots to the Church of the East.

The Church of the East was headed by the Patriarch of the East, continuing a line that, according to its tradition, stretched back to the Apostolic Age, and the christianization of the Assyrian people and other ethnic communities in western provinces of the Persian Empire. Particularly so in the historical region of Mesopotamia, including the province of Asōristān and several minor independent Mesopotamian Neo-Assyrian kingdoms of Osroene, Adiabene, Beth Garmai, Beth Nuhadra and Assur.