Ishoʿyahb lived through this momentous period, and is said to have met both the Roman emperor Heraclius and the second Moslem caliph ʿUmar ibn al-Khattab.
[2] Ishoʿyahb studied at the School of Nisibis when it was under the presidency of the controversial theologian Hnana, who searched for common theological ground between the Nestorianism of the Church of the East and the Chalcedonian doctrines held in the Roman empire.
Although little is known of the content of Ishoʿyahb’s discussions with Heraclius, he evidently persuaded the emperor that, despite its traditional reverence for the teachings of Theodore of Mopsuestia, the doctrinal position of the Church of the East was orthodox.
He was asked for his views on monoenergism, the doctrine of the single energy recently espoused by the patriarchate of Constantinople, and responded with a confession of faith which was accepted by the Roman bishops.
[3] Ishoʿyahb II was patriarch during the Arab conquest of Iraq, and according to later Nestorian tradition approached the Moslem leaders to win guarantees for the treatment of Christians in the Sassanian empire.
[6] Saʿd carried off its gates, symbolising the rulership of central Iraq, to Kufa, and for the rest of his reign Ishoʿyahb resided at Karka d'Beth Slokh (modern Kirkuk) in Beth Garmai.
According to Dale T. Irvin: "Early in the seventh century Catholicos Yeshuyab II shared communion with the East Roman emperor when the former was sent on a diplomatic mission on behalf of the shah, but this was by then an exception.