Chalcedon and the Eastern–Oriental Orthodox division
About this date: 451 marks the controversy's decisive conciliar starting point, not the immediate creation of a single Oriental Orthodox institution. The separation and distinct church structures emerged over a long aftermath; the blanket label 'Monophysite' is inaccurate for the Oriental Orthodox churches.
Disputes over the Council of Chalcedon's Christological definition and its reception contributed to a durable rupture between churches that accepted the council and communities now known as the Oriental Orthodox churches. The division hardened through theological, linguistic, imperial, and regional conflicts; modern dialogues have found substantial Christological agreement without yet restoring full communion.