A number of East Syriac dioceses in Iran existed by the beginning of the fifth century, but they were not grouped into a metropolitan province in 410.
After establishing five metropolitan provinces in Mesopotamia, Canon XXI of the synod of Isaac provided that 'the bishops of the more remote dioceses of Fars, of the Islands, of Beth Madaye (Media), of Beth Raziqaye (Rai) and of the country of Abrshahr (Tus) must accept the definition established in this council at a later date'.
[1] By the end of the fifth century, there were at least three East Syriac dioceses in the Sassanian province of Media in western Iran.
[4] Because of its origins in a mass deportation of Roman Christians, the diocese of Hulwan was probably more populous than that of Hamadan during the late Sassanian period.
In 893 Eliya of Damascus listed Hulwan as a metropolitan province, with suffragan dioceses for Dinawar (al-Dinur), Hamadan, Nihawand and al-Kuj.
[6] Little is known about these suffragan dioceses, except for isolated references to bishops of Dinawar and Nihawand, and by the end of the twelfth century Hulwan and Hamadan were probably the only surviving centres of East Syriac Christianity in Media.
It is possible that its Christian population at the end of the thirteenth century was small indeed, and it is not known whether it was still the seat of a metropolitan bishop.
[9] The priest and secretary Ahaï was among the signatories of the acts of the synod of Babaï in 497, on behalf of the bishop Ahron 'of Beth Lashpar'.
[16] The bishop Ishoʿyahb of Susa was appointed metropolitan of Hulwan by the patriarch Yohannan III immediately after his consecration on 15 July 893.
[21] The metropolitan ʿAbd al-Masih 'of Hulwan and Rai' was present at the consecration of the patriarch ʿAbdishoʿ II in 1074, and died at an unknown date during his reign.