=The Two Civilizations.= This is one of the periods of thought resulting from the shiftings of distinct civilizations. We have already noted the influence of the struggles of the Orient and the Occident in the Persian wars and in the campaigns of Alexander; and we have lately seen an entirely new epoch ushered in by the invasions of the northern tribes into Rome. With the new epoch before us, we find ourselves confronted with another new ethnic situation. The civilization of the Mohammedan had grown in mighty strength in the East, had possessed itself of Asia Minor, northern Africa, and Spain, and was now facing Europe from the east, west, and south. All through the First Period of the Middle Ages the Christian and Mohammedan civilizations had been contestants for supremacy. Only as late as 732 the Mohammedan claim upon Europe had been defeated at the battle of Tours. Mohammed (570–632) converted the whole of Arabia to Islam during the ten years between his Hegira (622) and his death. His successors took Palestine (637), Syria (638), Egypt (647), Persia (710), all north Africa (by 707), invaded Spain (711), and were repulsed at Tours (732). All this occurred within a century, and for the next two hundred years (800–1000) the Mohammedans harassed Rome and the islands of the Mediterranean. With the two civilizations facing each other on the Mediterranean, only mutual religious fanaticism could stand in the way of their mutual cultural influence. In point of fact, because of fanaticism the cultures of the two civilizations during the first centuries of the Middle Ages touched each other but little. In those first centuries of the Middle Ages, when western Europe was shrouded in darkness, the schools of the Arabs at Bagdad, Basra, Kufa, and other cities were enjoying a splendid intellectual life. From 850 to 1100 the centre of learning of the world was in the Arabian cities of the East.[58] In 1100 the fanatical faction of the Arabians crushed this intellectual movement in the East, the scholars fled to Spain, and for a century longer Saracen learning flourished in Spain, especially in Cordova. In 1200 the Arabian orthodoxy made itself felt in Spain, and the Arabian scholars there had to find refuge among the Jews or Christians.