The Syriac Orthodox Patriarch of Antioch and All the East is the head of the Syriac Orthodox Church. According to tradition, the patriarchate of Antioch was established by Saint Peter in the 1st century AD, but split into two separate lines of patriarchs after the deposition of Patriarch Severus of Antioch in 518 over the issue of the Council of Chalcedon of 451. The non-Chalcedonian supporters of Severus went on to form what is now known as the Syriac Orthodox Church, whilst the Chalcedonians developed the church now known as the Greek Orthodox Church of Antioch.