At the onset of his tenure as patriarch, John exchanged letters with the archbishop Marutha of Tikrit concurrent with the Muslim conquest of Persia, which allowed Marutha to inform John of the persecution of Syriac non-Chalcedonians in the Sasanian Empire by the Nestorian archbishop Barsauma in the 5th century. Formerly, Syriac non-Chalcedonians in Iran had been prevented from corresponding with their coreligionists in the Roman Empire as they had been labelled as Roman sympathisers and spies by Nestorians.
Initially, John began exchanging correspondence with Archbishop Marutha of Tikrit at the start of his tenure, coinciding with the Muslim conquest of Persia. This allowed Marutha to keep John informed about the persecution of Syriac non-Chalcedonians in the Sasanian Empire by Nestorian Archbishop Barsauma during the 5th century. Before this, Syriac non-Chalcedonians in Iran were restricted from contacting their fellow Christians in the Roman Empire due to being viewed as Roman sympathizers and spies by Nestorians.