In the 9th century the patriarchate moved to Baghdad and then through various cities in what was then Assyria (Assuristan/Athura) and is now northern Iraq, south east Turkey and northwest Iran, including, Tabriz, Mosul, and Maragheh on Lake Urmia.
While Christianity had been introduced into Assyria then largely under the rule of the Parthian Empire in the first centuries AD, during the earliest period, leadership was unorganized and there was no established succession.
A number of these patriarchs are legendary, or have been included in the standard lists on dubious evidence according to some historians like Jean Maurice Fiey.
One such fashion was to fill in the inevitable gaps in the historical record to trace a succession of bishops in individual dioceses right back to the 1st century, preferably to an apostolic founder.
Shahlufa and Ahadabui, two late-3rd-century bishops of Erbil who had played a notable part in the affairs of the church of Seleucia-Ctesiphon, were 'converted' retrospectively into early patriarchs.
Fiey also claims these five phantom 'patriarchs' were included in all the later histories of the Church of the East, and by the 12th century their existence was an article of faith for the historian Mari bin Sulaiman.
According to Feiy, they are still included by courtesy in the traditional list of patriarchs of the Church of the East, even though most scholars agree that they never existed.
[26] Denha II is known to have been consecrated in Baghdad, thanks to the patronage of the Christian emir Haggi Togai, but may have been normally resident in the Mosul plain village of Karamlish.
[29] Shemʿon's brother the metropolitan Ishoʿyahb Bar Mama, who had been natar kursya throughout his reign, is first mentioned as patriarch in a colophon of 1539.
In 1552 a section of the Church of the East, angered by the appointment of minors to important episcopal positions by the patriarch Shemʿon VII Ishoʿyahb, revolted against his authority.
The rebels elected in his stead Sulaqa, the superior of the monastery of Rabban Hormizd near Alqosh, but were unable to consecrate him as no bishop of metropolitan rank was available, as canonically required.
Sulaqa went to Rome, where he made a satisfactory Catholic profession of faith and presented a letter, drafted by his supporters in Mosul, which set out his claims to be recognized as patriarch.
Eliya XI Denha died of plague in Alqosh on 29 April 1778, and was exceptionally buried in the town rather than the monastery, which had been abandoned and locked up following a Persian attack in 1743.
The date of Sulaqa's election in 1552 is not known, but he was confirmed as 'patriarch of Mosul' by the Vatican on 28 April 1553, and was martyred at the beginning of 1555, probably (according to a contemporary poem of ʿAbdishoʿ IV) on 12 January.
Shemʿon XXI Eshai was murdered in the United States in 1975 and succeeded in 1976 by Dinkha IV Hnanya, the first non-Patriarch of the Church of the East to be appointed not by hereditary succession since the 15th century.
The recognition of the Mosul patriarch Yohannan VIII Hormizd by the Vatican in 1830 marked the birth of the Chaldean Catholic Church.
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.
[38][35] 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.