The story of how Christianity reached the Aksumite court is told by the fifth century historian Rufinus, who says he heard it from one of the men involved. Two young Christians from Tyre, Frumentius and Aedesius, survived the killing of a ship's company on the Red Sea coast, were taken to the palace, and rose to positions of trust, Frumentius as tutor to the young heir. When the boy came of age Frumentius travelled to Alexandria to ask that a bishop be sent to the Christians of Aksum, and Athanasius consecrated Frumentius himself and sent him back. Ethiopian tradition knows him as Abba Salama, the father of peace, and as the Revealer of the Light.
A second document confirms the outline from an unfriendly source. Athanasius preserves a letter from the emperor Constantius II addressed to Ezana and his brother Saizana, asking them to send Frumentius to Egypt to be examined, because Constantius supported the Arian party and Frumentius had been ordained by Athanasius, whom he had driven from Alexandria. The request appears to have been ignored. That an emperor at Constantinople was writing to Aksum about the doctrinal loyalty of its bishop shows how quickly the kingdom had entered the wider Christian world.
The arrangement Frumentius began outlasted every empire involved in it. For sixteen hundred years the head of the Ethiopian church, the abun, was a monk sent from the Coptic patriarchate of Alexandria rather than an Ethiopian, an unusual dependency for so large and self-conscious a church. It ended only in 1959, when the Ethiopian Orthodox Tewahedo Church received its own patriarch and became autocephalous.