 The Holy Qurbana of Addai and Mari is one of the oldest Eucharistic prayers in Christianity, composed around the year 200 AD.The Church of the East was consolidated in 410 at the Council of Seleucia-Ctesiphon, held at the Sasanian capital, Selucia-Ctesiphon, which remained the seat of the Patriarchate of the Church of the East for over 600 years.The Mandaean religion, whose adherents according to their traditions are the original followers of John the Baptist, and who are considered to be the only surviving Gnostic group in the world, also originated in the region at this time (or slightly earlier during the Parthian era).