The Ecclesiastical History of Sozomen 50Some Indian Nations received Christianity at that Time through the Instrumentality of Two Captives, Frumentius and Edesius.

We have heard that about this period some of the most distant of the nations that we call Indians, to whom the preaching of Bartholomew was unknown, shared in our doctrine, through Frumentius, who became a priest and teacher of the sacred learning among them. But in order that we may know, even by the marvel of what happened in India, that the doctrine of the Christians ought to be received as a system not from man, as it seems a tissue of miracles to some, it is necessary to relate the reason for the ordination of Frumentius. It was as follows: The most celebrated philosophers among the Greeks explored unknown cities and regions. Plato, the friend of Socrates, dwelt for a time among the Egyptians, in order to acquaint himself with their manners and customs. He likewise sailed to Sicily for the sight of its craters, whence, as from a fountain, spontaneously issued streams of fire, which frequently overflowing, rushed like a river and consumed the neighboring regions, so that even yet many fields appear burnt and cannot be sown or planted with trees, just as they narrate about the land of Sodom. These craters were likewise explored by Empedocles, a man highly celebrated for philosophy among the Greeks, and who has expounded his knowledge in heroic verse. He set out to investigate this fiery eruption, when either because he thought such a mode of death preferable to any other, or because, to speak more truthfully, he perhaps knew not wherefore he should seek to terminate his life in this manner, he leaped into the fire and perished. Democritus of Coos explored many cities and climates and nations, and he says concerning himself that eighty years of his life were spent in traveling through foreign lands. Besides these philosophers, thousands of wise men among the Greeks, ancient and modern, devoted themselves to this travel. In emulation, Meropius, a philosopher of Tyre in Phoenicia, journeyed as far as India. They say he was accompanied by two youths, named Frumentius and Edesius; they were his relatives; he conducted their rhetorical training, and educated them liberally. After exploring India as much as possible, he set out for home, and embarked in a vessel which was on the point of sailing for Egypt. It happened that, from want of water or some other necessary, the vessel was obliged to stop at some port, and the Indians rushed upon it and murdered all, Meropius included. These Indians had just thrown off their alliance with the Romans; they took the boys as living captives, because they pitied their youth, and conducted them to their king. He appointed the younger one his cup-bearer; the older, Frumentius, he put over his house and made him administrator of his treasures; for he perceived that he was intelligent and very capable in business. These youths served the king usefully and faithfully during a long course of years, and when he felt his end approaching, his son and wife surviving, he rewarded the good-will of the servants with liberty, and permitted them to go where they pleased. They were anxious to return to Tyre, where their relatives resided; but the king's son being a minor, his mother besought them to remain for a little while and take charge of public affairs, until her son reached the years of manhood. They yielded to her entreaties, and directed the affairs of the kingdom and of the government of the Indies. Frumentius, by some Divine impulse, perhaps because God moved him spontaneously, inquired whether there were any Christians in India, or Romans among the merchants, who had sailed thither. Having succeeded in finding the objects of his inquiry, he summoned them into his presence, treated them with love and friendliness, and convened them for prayer, and the assembly was conducted after the Roman usage; and when he had built houses of prayer, he encouraged them to honor God continually.

When the king's son attained the age of manhood, Frumentius and Edesius besought him and the queen, and not without difficulty persuaded the rulers to be separated from themselves, and having parted as friends, they went back as Roman subjects. Edesius went to Tyre to see his relatives, and was soon after advanced to the dignity of presbyter. Frumentius, however, instead of returning to Phoenicia, repaired to Alexandria; for with him patriotism and filial piety were subordinate to religious zeal. He conferred with Athanasius, the head of the Alexandrian Church, described to him the state of affairs in India, and the necessity of appointing a bishop over the Christians located in that country. Athanasius assembled the endemic priests, and consulted with them on the subject; and he ordained Frumentius bishop of India, since he was peculiarly qualified and apt to do much service among those among whom he was the first to manifest the name of Christian, and the seed of the participation in the doctrine was sown. Frumentius, therefore, returned to India, and, it is said, discharged the priestly functions so admirably that he became an object of universal admiration, and was revered as no less than an apostle. God highly honored him, enabling him to perform many wonderful cures, and to work signs and wonders. Such was the origin of the Indian priesthood.