From what I have learned and read, the Church of the East isn’t technically Nestorian. A lot of people mistakenly believe that the CotE separated at the Council of Ephesus over the Nestorianism, but, it had actually done so, slightly earlier in 424. You see the Roman Empire and the Persian Empire(where the majority of the Church of the East was found) were bitter rivals, and so when in 380 Christianity became the state religion of the empire, the Persians began to view their Christian subjects as a potential 5th column and began to ramp up the already devastating persecutions. Thus, Catholicos Mar Dadisho and the Persian Bishops met and decided that they would not subject to any external power on disciplinary or theological issues, I guess in a effort to appease the Persian Emperor and in effect severing their ties to the wider Church especially the Church within the Roman Empire. Thus the condemnation of Nestorianism at the Council of Ephesus didn’t take “effect” making it a haven for Nestorian exiles, eventually thriving enough as to gain sympathy among many Bishops and Priests. At least that’s how I understand it, if anybody can correct me please do so.
