The province consisted of a number of dioceses in the region of Beth Aramaye, between Basra and Kirkuk, which were placed under the patriarch's direct supervision at the synod of Yahballaha I in 420.
According to Eliya of Damascus, there were thirteen dioceses in the province of the patriarch in 893: Kashkar, al-Tirhan (Tirhan), Dair Hazql (an alternative name for al-Nuʿmaniya, the chief town in the diocese of Zabe), al-Hira (Hirta), al-Anbar (Piroz Shabur), al-Sin (Shenna d'Beth Ramman), ʿUkbara, al-Radhan, Nifr, al-Qasra, 'Ba Daraya and Ba Kusaya' (Beth Daraye), ʿAbdasi (Nahargur) and al-Buwazikh (Konishabur or Beth Waziq).
Eliya's list helps to confirm the impression given by the literary sources, that the East Syrian communities in Beth Aramaye were at their most prosperous in the tenth century.
However, East Syrian communities may also have persisted in districts which no longer had bishops: a manuscript of 1276 was copied by a monk named Giwargis at the monastery of Mar Yonan 'on the Euphrates, near Piroz Shabur which is Anbar', nearly a century and a half after the last mention of a bishop of Anbar.
It was said to have been founded by the apostle Mari in the first century, several decades before the establishment of a diocese in the Persian capital Seleucia-Ctesiphon.
[9] By 1222 the guardianship of the vacant patriarchal throne, for centuries a privilege of the bishops of Kashkar, was in the hands of the metropolitans of Beth Huzaye.
[10] The East Syrian diocese of Hirta (al-Hira, الحيرة) is first attested in 410, but may have been a fourth-century foundation.
He was a contemporary of the East Syrian monk Rabban Khudahwi, and helped him build the monastery of Beth Hale.
[21] The bishop Joseph of al-Hira (Hirta) was appointed metropolitan of Maishan during the reign of the patriarch Mari (987–99).
[24] The secretary Shila was among the signatories of the acts of the synods of Acacius in 486 (as a deacon) and Babai in 497 (as a priest), on behalf of the bishop Mihrnarsai of Zabe.
[30] The bishop Shlemun of Zabe (al-Zawabi) was appointed metropolitan of Fars during the reign of the patriarch Mari (987–99).
[13] The secretary Marqos was among the signatories of the acts of the synod of Babai in 497, on behalf of the bishop Brikhishoʿ of Beth Daraye.
[35] The priest Yohannan was among the signatories of the acts of the synod of Babai in 497, on behalf of the bishop Shamaʿ of Piroz Shabur.
[41] In 921/2 the bishop Eliya of Piroz Shabur "confessed his sin before the patriarch Abraham and stated in a written confession that he had sinned and erred in holding that Our Lord had not eaten the bread which he blessed and broke and gave to the disciples on the day of the Passover".
[42] The bishop Sabrishoʿ of Piroz Shabur (al-Anbar) was appointed metropolitan of ʿIlam during the reign of the patriarch Mari (987–99).
[34] The bishop Mari ibn ʿAus of 'Radhan' was transferred to the diocese of Anbar by the patriarch Sabrishoʿ III shortly after his consecration in 1063/4.
[45] The Nestorian diocese of Tirhan was founded in the sixth century, probably to counter the influence of the important Jacobite centre of Tagrit.
[29] The bishop Miles 'of Shenna' was among the signatories of the acts of the synod of Ishoʿyahb I in 585 and the agreement of Bar Qaiti in March 598.
[40] The monk Makkikha, superior of the monastery of Beth ʿAbe, was elected bishop of Shenna by its East Syrian community in 900 after visiting Baghdad to attend the consecration of the patriarch Yohannan IV.
ʿAbd al-Masih abdicated shortly afterwards and was replaced by Abu ʿAli Tahir of the Greek Palace.
[62] The diocese of Qasr is first mentioned in connection with an incident that took place in the reign of Sliba-zkha (714–28), when the caliph ʿAbd al-Malik visited 'the church of the throne that is called the "White Fortress" (al-qasr al-abyad)'.
[64] He wrote an account of an incident that took place at Qasr in ʿAbdishoʿ's reign, during an inundation of the Tigris, which was later quoted at length by the historian Mari.
[66] Naʿaman Ibn Saʿada was consecrated bishop of 'al-Qasr' at an unknown date during the reign of the patriarch ʿAbdishoʿ II (1074–90).
[74] Baghdad, the capital of the Abbasid Caliphate, was the seat of the East Syrian patriarchs between the eighth and thirteenth centuries, and is frequently mentioned in the various literary sources in connection with the ceremonies attending their elections, consecrations, and burials.
These sources mention several East Syrian monasteries and churches in or near Baghdad used as residences by the East Syrian patriarchs at different periods, and the relevant references have been conveniently collected by the French scholar J. M. Fiey, who also precisely localised most of the sites concerned.
He died quite by chance in Baghdad in 1281, during his first visit to the city for sixteen years, and was probably the last East Syrian patriarch to be buried there.
His successor Yahballaha III was consecrated in Baghdad in 1281, but also avoided the city for much of his reign, preferring to reside first in Eshnuq and finally in Maragha.
However, a poem written in Karamlish in 1295 mentions that he restored the chapels and apartments in the Greek Palace, probably during the reign of the sympathetic il-khan Arghun, and built a "very beautiful gallery for counsel, recreation, and the reunions of the fathers".
[citation needed] The accession of the il-khan Ghazan in 1295 was followed immediately by a persecution of Christians in Baghdad and several other cities, in which a number of churches were confiscated.
The Moslems also recovered the palace of Duwaidar ʿAla al-Din, which had been taken from them and given to Makkikha II by Hulegu after the city's capture in 1259, and required the East Syrians to remove for reburial elsewhere the remains of the patriarchs Makkikha II and Denha I and other prominent clerics and monks buried there.