section_path: Churches and denominations/Church of the East
section_name: Church of the East
paragraph_text: Church of the East
  
  The Church of the East, which was part of the Great Church, shared communion with those in the Roman Empire until the Council of Ephesus condemned Nestorius in 431. Continuing as a dhimmi community under the Rashidun Caliphate after the Muslim conquest of Persia (633–654), the Church of the East played a major role in the history of Christianity in Asia. Between the 9th and 14th centuries, it represented the world's largest Christian denomination in terms of geographical extent. It established dioceses and communities stretching from the Mediterranean Sea and today's Iraq and Iran, to India (the Saint Thomas Syrian Christians of Kerala), the Mongol kingdoms in Central Asia, and China during the Tang dynasty (7th–9th centuries). In the 13th and 14th centuries, the church experienced a final period of expansion under the Mongol Empire, where influential Church of the East clergy sat in the Mongol court.
  
  The Assyrian Church of the East, with an unbroken patriarchate established in the 17th century, is an independent Eastern Christian denomination which claims continuity from the Church of the East —in parallel to the Catholic patriarchate established in the 16th century that evolved into the Chaldean Catholic Church, an Eastern Catholic church in full communion with the Pope. It is an Eastern Christian church that follows the traditional christology and ecclesiology of the historical Church of the East. Largely aniconic and not in communion with any other church, it belongs to the eastern branch of Syriac Christianity, and uses the East Syriac Rite in its liturgy.
  
  Its main spoken language is Syriac, a dialect of Eastern Aramaic, and the majority of its adherents are ethnic Assyrians, mostly living in Iran, Iraq, Syria, Turkey, India (Chaldean Syrian Church), and in the Assyrian diaspora. It is officially headquartered in the city of Erbil in northern Iraqi Kurdistan, and its original area also spreads into south-eastern Turkey and north-western Iran, corresponding to ancient Assyria. Its hierarchy is composed of metropolitan bishops and diocesan bishops, while lower clergy consists of priests and deacons, who serve in dioceses (eparchies) and parishes throughout the Middle East, India, North America, Oceania, and Europe (including the Caucasus and Russia).
  
  The Ancient Church of the East distinguished itself from the Assyrian Church of the East in 1964. It is one of the Assyrian churches that claim continuity with the historical Church of the East, one of the oldest Christian churches in Mesopotamia. It is officially headquartered in the city of Baghdad, Iraq. The majority of its adherents are ethnic Assyrians.