"The Jews say, 'Ezra is a son of God,' and the Christians say, 'The Messiah is a son of God' ... they resemble the saying of the Infidels of old.... They take their teachers and their monks and the Messiah, son of Mary, for Lords beside God, though bidden to worship one God only. There is no God but He! Far what from his glory be what they associate with Him."--_The Kuran_. The Prophet of Arabia had scarcely been committed to the keeping of earth, when on all sides rebellion against his rule arose. The unity that he had laboured so long to create was still in embryo, but the seed of it was living, and developed rapidly to its full fruition. In the political sphere his achievement is not limited to the immediate security of his dominion. He had inculcated, mainly by the forcible logic of the sword, the idea of union and discipline, and had restored in mightier degree the fallen greatness of his land. Traditions of Arabian prosperity during the time when it was the trade route from Persia and the East to Petraea, Palestine, and even Asia Minor lingered in the native mind. The caravan routes from Southern Arabia, famous in Biblical story, had made the importance of such cities as Mecca and Sana, but with the maritime enterprise of Rome their well-being declined, and the consequent distress in Yemen induced its tribes to emigrate northwards to Mecca, to Syria, and the Central Desert. Southern Arabia never recovered from the blow to its trade, and in the sixth century Yemen became merely a dependency of Persia. Central Arabia was an unknown country, inhabited by marauding tribes in a constant state of political flux; while Hira, the kingdom to the east of the desert on the banks of the Euphrates, had become a satrapy of Persia early in the century in which Mahomet lived, and Heraclius by frequent inroads had reduced the kingdom of Palmyra to impotence. Arabia was ripe for the rise of a strong political leader; for it was flanked by no powerful kingdom, and within itself there was no organisation and no reliable political influence.