At the city's foundation in the early 9th century, it was included in the diocese of Qardu, a suffragan of the Archdiocese of Nisibis in the Church of the East. In c. 900, the diocese of Bezabde was moved and renamed to Gazarta (Jazirat Ibn ʿUmar in Syriac), and partially assumed the territory of the diocese of Qardu, which was also moved and renamed to its new seat Tamanon, having previously been based at Penek. Tamanon declined and at some point after the mention of its last bishop in 1265, its diocese was subsumed into the diocese of Gazarta.