Iran: Mar Elias (Eliya), the Nestorian bishop of the Urmia Plain village of Geogtapa, c.1831.

Nestorianism is a Christological doctrine advanced by Nestorius, Patriarch of Constantinople from 428-431. Nestorius and his teachings were eventually condemned as heretical at the First Council of Ephesus in 431 and the Council of Chalcedon in 451, leading to the Nestorian Schism in which churches supporting Nestorius broke with the rest of the Christian Church. Afterward many of Nestorius' supporters relocated to Sassanid Persia, where they affiliated with the local Christian community, known as the Church of the East. Subsequently the Church of the East became increasingly Nestorian in doctrine, leading it to be known alternately as the Nestorian Church.