Conference of Addis Ababa
The Conference of Addis Ababa was a meeting of the Oriental Orthodox Churches in Addis Ababa, Ethiopia from 15 to 21 January 1965. Hosted nominally by Abuna Basilios (head of the Ethiopian Orthodox Tewahedo Church), but effectively by Abuna Theophilos, this meeting was momentous as there had been no such collective meeting of the various non-Chalcedonian churches since the 5th century at Ephesus.
Source: Wikipedia — Conference of Addis Ababa (CC BY-SA 4.0)