The article is an attempt to restore the fate of the church authority in the lands of Greater Armenia and Armenia Minor, which on the eve of the conquests of the Arab Muslims, being as parts of the Byzantine Empire, had been subordinated either to the Patriarchates in Constantinople and Antioch, or Catholicosate in Dvin, and after the Arab-Byzantine wars of the second half 7th c. they went to the Umayyad Caliphate (661–750). According to the author’s calculations, in the early 8th c. with the possible intervention of the Islamic authorities there were formed in the lands of the former Byzantine Armenia at least three major dioceses of the Syrian Jacobite Church, which, like the Armenian Church, firmly adhered to the anti-Chalcedonite position and came under the supreme authority of the Arabs. Three more such church units were formed at the end of the same century. Two of the six dioceses of the Syrian Jacobite church, were occupied the former canonical territories of the Constantinople Patriarchate, two – the Patriarchate of Antioch and two more – the Catholicosate of Dvin.