The Nestorians are a branch of the ancient Christian Church, and derive their name from Nestorius, a native of Syria and Bishop of Constantinople, who was excommunicated by the third General Council at Ephesus, in the year 431. The cause of his condemnation was probably the desire to humble the occupant of the see of Constantinople, which had begun to eclipse its sister patriarchates, rather than any real doctrinal errors. He was banished to Arabia Petraea, then to Libya, and finally died in Upper Egypt. But his cause was the cause of his countrymen, and he had influential friends in the patriarchate of Antioch, who denied the fairness of his trial and the justice of his condemnation. His case was ardently espoused by many young men from Persia in the famous school of Edessa (now Oorfa), and though these were expelled, and the school itself was destroyed in the year 489, by order of the Emperor Zeno, the banished youths carried home with them a warm sympathy for Nestorius, and various causes combined to extend it among the Persian ecclesiastics. In the year 498, the sect had so multiplied, as to have the appointment of the Archbishop of Seleucia and Ctesiphon, who then declared himself Patriarch of the East. "This sect continued to flourish, though occasionally persecuted, under the Persians, the Saracens, and the Tartars. They had celebrated schools for theology and general education. For centuries they maintained missions in Tartary, China, and other eastern regions. Their churches were scattered from Syria and Cyprus to Pekin, and from the coast of Malabar and Ceylon to the borders of Siberia. Early in the eleventh century, Unkh Khan, a Tartar prince on the northern borders of China, invited Nestorian missionaries among his people, and himself became the famous Prester John. Gengis Khan and several of his sons and grandsons, who conquered China and almost all Asia and a part of Europe, were connected with Prester John by marriage. Several of them had Christian wives, and one of them at least professed himself a Christian. Under some of this dynasty, Central Asia was comparatively a civilized country; and Christian travellers passed with safety from the banks of the Euphrates to Samarcand and Pekin. Some of the Chinese emperors favored Christianity, and ordered the erection of numerous churches. Meanwhile the sword of Moslem fanaticism was advancing eastward. Bagdad fell before it, and all the country on the Euphrates; then Persia, then Cabul, and the regions of the north. The Nestorian Church being thus crushed at home, its missions languished. And finally, about the year 1400, Tamerlane, who has been called 'the greatest of conquerors,' swept like a whirlwind over the remains of Nestorian Christianity, prostrating everything in his course."1