War, the bitterest theology, and the usual vices of mankind constituted Byzantine life of those days. It was picturesque, it was romantic; it had little sweetness or light. When Byzantium and Persia were not fighting the barbarians from the north, they wasted Asia Minor and Syria in dreary and destructive hostilities. Even in close alliance these two empires would have found it a hard task to turn back the barbarians and recover their prosperity. The Turks or Tartars first come into history as the allies first of one power and then of another. In the sixth century the two chief antagonists were Justinian and Chosroes I; in the opening of the seventh the Emperor Heraclius was pitted against Chosroes II (580). At first and until after Heraclius had become Emperor (610) Chosroes II carried all before him. He took Antioch, Damascus and Jerusalem and his armies reached Chalcedon, which is in Asia Minor over against Constantinople. In 619 he conquered Egypt. Then Heraclius pressed a counter attack home and routed a Persian army at Nineveh (627), although at that time there were still Persian troops at Chalcedon. In 628 Chosroes II was deposed and murdered by his son, Kavadh, and an inconclusive peace was made between the two exhausted empires. Byzantium and Persia had fought their last war. But few people as yet dreamt of the storm that was even then gathering in the deserts to put an end for ever to this aimless, chronic struggle. While Heraclius was restoring order in Syria a message reached him. It had been brought in to the imperial outpost at Bostra south of Damascus; it was in Arabic, an obscure Semitic desert language, and it was read to the Emperor, if it reached him at all, by an interpreter. It was from someone who called himself “Muhammad the Prophet of God.” It called upon the Emperor to acknowledge the One True God and to serve him. What the Emperor said is not recorded. A similar message came to Kavadh at Ctesiphon. He was annoyed, tore up the letter, and bade the messenger begone. This Muhammad, it appeared, was a Bedouin leader whose headquarters were in the mean little desert town of Medina. He was preaching a new religion of faith in the One True God. “Even so, O Lord!” he said; “rend thou his Kingdom from Kavadh.” XLII THE DYNASTIES OF SUY AND TANG IN CHINA Throughout the fifth, sixth, seventh and eighth centuries, there was a steady drift of Mongolian peoples westward. The Huns of Attila were merely precursors of this advance, which led at last to the establishment of Mongolian peoples in Finland, Esthonia, Hungary and Bulgaria, where their descendants, speaking languages akin to Turkish, survive to this day. The Mongolian nomads were, in fact, playing a role towards the Aryanized civilizations of Europe and Persia and India that the Aryans had played to the Ægean and Semitic civilizations ten or fifteen centuries before.