Short answers, pulled from the story.
The term Oriental Orthodox Churches was officially adopted by the faithful at the Conference of Addis Ababa in 1965. This decision was made by five participating churches before the Eritrean Church gained autocephaly.
The label Monophysite implies that Christ had only a divine nature and no human nature, which is a pejorative term applied by imperial Roman counterparts. The churches prefer the term Miaphysite, which asserts that Christ has one united nature that is both fully divine and fully human.
The Council of Chalcedon in AD 451 caused the division between the Oriental Orthodox Churches and the imperial Roman church. This council declared that Christ existed in two complete natures, one human and one divine, which the Oriental Orthodox hierarchs rejected as tantamount to Nestorianism.
Under Umayyad rule, Christians were taxed at a higher rate than Muslims, which drove merchants toward Islam and undermined the economic base of the church. Despite the conquest, the Muslim leader Amr ibn al-As took none of the property of the churches and committed no act of spoilation.
The Conference of Addis Ababa established the Standing Conference of Oriental Orthodox Churches in 1965. This event marked a turning point that brought together the autocephalous churches to foster cooperation and mutual recognition.