Orthodox origins ar in time of apostols.Until 1054.Church was unseparated,but then Roman pope took to him right to be "visible head of universal Church".The Eastern patriarks(of Constantinopolis,Alexandria,Antiohia and Jerusalem)didn't agreed with his aspirations and thay agreed that there is no universal head exept Christ.
Using his new right,pope is changeing "credo"and adding new teaching known as filioqve.
That shisma maybe cold be medicined,but pope sends crusadors in Byzantine impery to concor "shismatics".Catholic priests had murdered orthodox bishops,raped orthodox nanys and robed relics.In Athos they sloughterd or burned about 950 monks.Then the eastern christians started to to hait the western barbarians and decided beter to be concord by islamic Turks than to confes popes authority.
Now there is 9 patriaks.They ar in Istambul,Alexandria, Antiohia(temporarly in Damascus),Jerusalem,Moscow,Belgrade,Sofia,Bukurest and Tbilisi.
Now,situation is very different.Church have contacts with catholics,specialy since 2.Vatican council.Unity is still unposible,but thnaks to God,there is no hait anymore.Orthodox nations ar now very open to others.
Orthodox ar majority in next states:Grece,Bulgaria,Serbia,Montenegro,Russia,Romania,Belarus,Ukraina,Gruzia(Georgia),Cyprus and Macedonia.