Baghdad Episcopal See

The patriarchal see of the Church of the East was fixed in 410 at the Council of Seleucia-Ctesiphon; the patriarch ruled from Kokhe in the Sasanian capital. When the caliph al-Mansur founded Baghdad nearby in 762, the patriarch was compelled to move there, and the city became the heart of a church stretching from Mesopotamia to India, Central Asia and Tang China.

The Mongol sack of 1258 at first spared the Christians: Hulagu's wife Doquz Khatun interceded for them, and Patriarch Makkikha II was granted the caliphal palace as a church.

The Ilkhan Ghazan's conversion to Islam in 1295 ended this favor, and Timur's storm of Baghdad in 1401 shattered the community. In the fifteenth century the patriarchs withdrew to Alqosh near Mosul. The schism of 1552 produced a rival Chaldean Catholic line when Yohannan Sulaqa was consecrated in Rome; by 1830 two patriarchates had settled into lasting separation.