In the history of Christianity, the first seven Ecumenical Councils, from the First Council of Nicaea (325) to the Second Council of Nicaea (787), represent an attempt to reach an orthodox consensus and to establish a unified Christendom. The East-West Schism, formally dated to 1054, was still almost three centuries off. Eastern Orthodox, Catholic, and Anglican churches all trace their clergy by apostolic succession back to this period and earlier, see Early Christianity. However, breaks of unity that still persist today had occurred even during this period. The Assyrian Church of the East rejected the Council of Ephesus (431). The Oriental Orthodox churches recognise the first three and consider the Second Council of Ephesus (449) to be the Fourth Ecumenical Council. The Roman Catholic Ch