 Complete the following phrase:  After AD 639 Egypt was ruled by its Islamic conquerors from Arabia, and the treatment of the Coptic Christians ranged from tolerance to open persecution. In the 12th century, the church relocated its seat from Alexandria to Cairo. The same century also saw the Copts become a religious minority. During the 14th and 15th centuries, Nubian Christianity was supplanted by Islam. In 1959, the Ethiopian Orthodox Tewahedo Church was granted autocephaly. This was extended to the Eritrean Orthodox Tewahedo Church in 1998 following the successful Eritrean War of Independence from Ethiopia. Since the 