Mor Yuhanon (John) became a monk, studied and was ordained a priest in the Monastery of Mor Zacchaeus (Zakai) near Callinicus (Al-Raqqa). In February, 846, he was chosen and consecrated patriarch of Antioch by the Holy Synod which met at the Monastery of Shila near Sarug. In this meeting of the Synod, he wrote twenty-five canons, followed by a table indicating the degrees of consanguinity which forbid marriage. In 869, he called a second Synod to a meeting at Kfar Tutho, in which he issued eight canons for the offices of Patriarch and the Mapheryono (Catholicos), an abridgement of which may be found in the Hudoye (Nomocanon). There is also a tract in fifteen pages on the division of inheritance according to ecclesiastical laws, which may have been compiled by them, if not by John II. He also wrote a Synodical letter to Joseph, patriarch of Alexandria, and received a reply from him. He ordained eighty-six metropolitans and bishops, and died on the third of January.

(History of Syriac Literature and Sciences, Patriarch Ignatius Ephrem I Barsoum, Presseggiata Press, p 124/5)