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According to Church history, the Apostleship of Edessa (Assyria) is alleged to have been founded by Shimun Keepa (Peter) (33–64), Thoma Shlikha, (Saint Thomas), Tulmay (St. Bartholomew the Apostle) and of course Mar Addai (St. Thaddeus) of the Seventy disciples. Saint Thaddeus was martyred c.66 AD.


Thomas the Apostle Brother of Jesus 

Early bishops

Bishops of Seleucia-Ctesiphon

Around 280, visiting bishops consecrated Papa bar Aggai as Bishop of Seleucia-Ctesiphon, thereby establishing the succession. With him, heads of the church took the title Catholicos.

Metropolitans of Seleucia-Ctesiphon

Isaac was recognised as 'Grand Metropolitan' and Primate of the Church of the East at the Synod of Seleucia-Ctesiphon in 410. The acts of this Synod were later edited by the Patriarch Joseph (552–567) to grant him the title of Catholicos as well. This title for Patriarch Isaac in fact only came into use towards the end of the fifth century.

Catholicoi of Seleucia-Ctesiphon

With Dadisho, the significant disagreement on the dates of the Catholicoi in the sources start to converge. In 424, under Mar Dadisho I, the Church of the East declared itself independent of all the Church of the West (Emperor Justinian's Pentarchy); thereafter, its Catholicoi began to use the additional title of Patriarch. During his reign, the Council of Ephesus in 431 denounced Nestorianism.

In 544 the Synod of Mar Aba I adopted the ordinances of the Council of Chalcedon.[14]

From 628, the Maphrian also began to use the title Catholicos. See the List of Maphrians for details.

In 775, the seat transferred from Seleucia-Ctesiphon to Baghdad, the recently established capital of the ʿAbbasid caliphs.

1. Eliya line
Based in Alqosh.

In 1780, a group split from the Eliya line and elected:

In 1830, following the death of the Amid patriarchal administrator Augustine Hindi, he was recognised by the Vatican as patriarch of Babylon of the Chaldeans and the Mosul and Amid patriarchates were united under his leadership. This event marked the birth of the since unbroken patriarchal line of the Chaldean Catholic Church.

2. Shemʿon line
Based in AmidSiirtUrmia and Salmas;

Shemʿon line reintroduced hereditary succession in 1600; not recognised by Rome; moved to Qochanis

Shemʿon line in Qochanis formally broke communion with Rome:

3. Josephite line
Based in Amid, split from the Eliya line;


The Eliya line (1) in Alqosh ended in 1804, having lost most of its followers to Yohannan VIII Hormizd, a member of the same family, who became a Catholic and in 1828, after the death of a rival candidate, a nephew of the last recognized patriarch of the Josephite line in Amid (3), was chosen as Catholic patriarch. Mosul then became the residence of the head of the Chaldean Catholic Church until the transfer to Baghdad in the mid-20th century. For subsequent Chaldean Catholic patriarchs, see List of Chaldean Catholic patriarchs of Baghdad.

The Shemʿon line (2) remained the only line not in communion with the Catholic Church. In 1976 it officially adopted the name "Assyrian Church of the East". For subsequent patriarchs in this line, see List of patriarchs of the Assyrian Church of the East.

Numeration of the Eliya line patriarchs

Since patriarchs of the Eliya line bore the same name (Syriac: ܐܠܝܐ / Elīyā) without using any pontifical numbers, later researchers were faced with several challenges, while trying to implement long standing historiographical practice of individual numeration. First attempts were made by early researchers during the 18th and 19th century, but their numeration was later (1931) revised by Eugène Tisserant, who also believed that during the period from 1558 to 1591 there were two successive Eliya patriarchs, numbered as VI (1558-1576) and VII (1576-1591), and in accordance with that he also assigned numbers (VIII-XIII) to their successors. That numeration was accepted and maintained by several other scholars. In 1966 and 1969, the issue was reexamined by Albert Lampart and William Macomber, who concluded that in the period from 1558 to 1591 there was only one patriarch (Eliya VI), and in accordance with that appropriate numbers (VII-XII) were reassigned to his successors. In 1999, same conclusion was reached by Heleen Murre-van den Berg, who presented additional evidence in favor of the new numeration. Revised numeration was accepted in modern scholarly works, with one notable exception.

The Shimun line

In 1553, Mar Yohannan Sulaqa, willing to separate from the Church of the East's Patriarchal See of Alqosh, an Assyrian town in the Assyrian homeland, went to Rome asking for his appointment as Patriarch. He was consecrated in St. Peter's Basilica on 9 April 1553.

The Josephite line of Amid

The Catholic Patriarchs based in Amid, now Diyarbakır in southeastern Turkey, began with Joseph I who in 1667 became Catholic, obtained from the Turkish civil authorities in 1677 recognition of his independence from the non-Catholic patriarchal see of Alqosh. In 1681, Joseph I was recognized by Rome as "patriarch of the Chaldean nation deprived of its patriarch", because of the irregular situation in which the Shimun line had fallen since Shimun X. The numbering of the ensuing list reflect this conflict.

From 1830, the post of Catholic patriarch continued under Yohannan VIII Hormizd as Patriarch of Babylon and head of what is now called the Chaldean Catholic Church.

The Alqosh/Mosul line

In the 17th and 18th centuries, Alqosh was the seat of what, until the setting up of the Shimun line, had been the only patriarchal line, tracing its origins from the Apostle Thomas in the 1st century. This line is called the Eliyya line, because of the name that each of its successive patriarchs assumed. In 1771, the Alqosh Patriarch Eliyya XII Denkha (1722–1778) entered communion with the Catholic Church. However, on his death in 1778, his successor Eliyya XIII Ishoʿyahb, after obtaining recognition by Rome, quickly repudiated the union and returned to the traditional doctrine. His cousin Yohannan VIII Hormizd professed the Catholic faith and won others to the same faith. When Eliyya IX Ishoʿyahb died in 1804, no successor was elected and Yohannan Hormizd remained the only representative of the line. Rome recognized him in 1783 as metropolitan bishop of Mosul and administrator of the Alqosh/Mosul patriarchate. Only in 1830, after the death in 1827 of Augustine Hindi, the representative of the Josephite line, who had also been under consideration for recognition as the Catholic patriarch, was he acknowledged by Rome as patriarch.

On 19 February 2022, Pope Francis acceded to the request of the Synod of Bishops of the Chaldean Church and changed this title to Patriarch of Baghdad of the Chaldeans.

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