The Chaldean Church
Autonomous since 431.
The Church of the East rejected the Council of Ephesus (431). Flourishing in Mesopotamia and Persia, it evangelised India and China from the 4th to the 8th century. The Chaldean church is the Catholic branch of this church, which is also called the Assyrian Church of the East. Sent to Rome, the monk Jean Simon Soulaka was elected patriarch in 1551 and recognised by Rome as patriarch of the Chaldeans in 1553. In 1830, the Metropolitan of Mosul, Jean Hormizd II, was confirmed by Pope Pius VIII and given the title of Chaldean patriarch of Babylon. Under Emmanuel II Thomas (1900-1947), the majority of non-Catholic Chaldeans rallied to the Catholic Church. The Patriarch of Babylon of the Chaldeans resides in Baghdad.
His church has more than 1 million faithful (Iraq, Iran, Syria, Turkey, Lebanon, Jordan, and diaspora). The Assyrian Church (not in communion with Rome) has two patriarchs and approximately 300,000 faithful.