The Metropolitanate of Nisibis was an East Syriac metropolitan province of the Church of the East, between the fifth and seventeenth centuries. The ecclesiastical province of Nisibis (Syriac: Nisibin, , often abbreviated to Soba, ) had a number of suffragan dioceses at different periods in its history, including Arzun, Beth Rahimaï, Beth Qardu (later renamed Tamanon), Beth Zabdaï, Qube d’Arzun, Balad, Shigar (Sinjar), Armenia, Beth Tabyathe and the Kartawaye, Harran and Callinicus (Raqqa), Maiperqat (with Amid and Mardin), Reshaïna, Qarta and Adarma, Qaimar and Hesna d'Kifa. Aoustan d'Arzun and Beth Moksaye were also suffragan dioceses in the fifth century.
Background
In 363 the Roman emperor Jovian was obliged to cede Nisibis and five neighbouring districts to Persia to extricate the defeated army of his predecessor Julian from Persian territory. The Nisibis region, after nearly fifty years of rule by Constantine and his Christian successors, may well have contained more Christians than the entire Sassanian empire, and this Christian population was absorbed into the Church of the East in a single generation. The impact of the cession of Nisibis on the demography of the Church of the East was so marked that the province of Nisibis was ranked second among the five metropolitan provinces established at the synod of Isaac in 410, a precedence apparently conceded without dispute by the bishops of the three older Persian provinces relegated to a lower rank. The metropolitan of Nisibis ranked below the metropolitan of Ilam, but above the metropolitans of Maishan, Adiabene and Beth Garmaï.
The bishop of Nisibis was recognised in Canon XXI of the synod of Isaac as 'metropolitan of Arzun, of Qardu, of Beth Zabdaï, of Beth Rahimaï, of Beth Moksaye, and of the bishops to be found there', and the bishops Daniel of Arzun, Samuel 'of Arzun for Baita d'Aoustan', Daniel of Beth Moksaye, and Abraham of Beth Rahimaï were confirmed as his suffragans.
Ecclesiastical history
The bishop of Nisibis was recognised in 410 as the metropolitan of Arzun (), Qardu (), Beth Zabdaï (), Beth Rahimaï () and Beth Moksaye (). These were the Syriac names for Arzanene, Corduene, Zabdicene, Rehimene and Moxoene, the five districts ceded by Rome to Persia in 363. The metropolitan diocese of Nisibis () and the suffragan dioceses of Arzun, Qardu and Beth Zabdaï were to enjoy a long history, but Beth Rahimaï is not mentioned again, while Beth Moksaye is not mentioned after 424, when its bishop Atticus (probably, from his name, a Roman) subscribed to the acts of the synod of Dadisho. Besides the bishop of Arzun, a bishop of 'Aoustan d’Arzun' (plausibly identified with the district of Ingilene) also attended these two synods, and his diocese was also assigned to the province of Nisibis. The diocese of Aoustan d'Arzun survived into the sixth century, but is not mentioned after 554.
During the fifth and sixth centuries three new dioceses in the province of Nisibis were founded in Persian territory, in Beth Arabaye (the hinterland of Nisibis, between Mosul and the Tigris and Khabur rivers) and in the hill country to the northeast of Arzun. By 497 a diocese had been established at Balad (the modern Eski Mosul) on the Tigris, which persisted into the fourteenth century. By 563 there was also a diocese for Shigar (Sinjar), deep inside Beth Arabaye, and by 585 a diocese for 'Beth Tabyathe and the Kartawaye', the country to the west of Lake Van inhabited by the Kartaw Kurds. David was the bishop of the Kurds of Kartaw during or immediately after the reign of Hnanisho I (686–698).
The famous School of Nisibis was an important seminary and theological academy of the Church of the East during the late Sassanian period, and in the last two centuries of Sassanian rule generated a remarkable outpouring of East Syriac theological scholarship.
Probably during the Umayyad period, the East Syriac diocese of Armenia was attached to the province of Nisibis. The bishop Artashahr of Armenia was present at the synod of Dadisho in 424, but the diocese was not assigned to a metropolitan province. In the late thirteenth century Armenia was certainly a suffragan diocese of the province of Nisibis, and its dependency probably went back to the seventh or eighth century. The bishops of Armenia appear to have sat at the town of Halat (Ahlat) on the northern shore of Lake Van.