No such transformation was near taking place in the case of the invasions of the Saracens in Southern Gaul; they continued to infest Aquitania, Septimania, and Provence; their robber-hordes appeared frequently on the coasts of the Mediterranean and the banks of the Rhone, at Aigues-Mortes, at Marseilles, at Arles, and in Camargue; they sometimes penetrated into Dauphine, Rouergue, Limousin, and Saintonge. The author of this history saw, at the commencement of the present century, in the mountains of the Cevennes, the ruins of the towers built, a thousand years ago, by the inhabitants of those rugged countries, to put their families and their flocks under shelter from the incursions of the Saracens. But these incursions were of short duration, and most frequently undertaken by plunderers few in number, who retreated precipitately with their booty. Africa was not, as Asia was, an inexhaustible source of nations burning to push onward, one upon another, to go wandering and settling elsewhere. The people of the north move willingly towards the south, where living is easier and pleasanter; but the people of the south are not much disposed to migrate to the north, with its soil so hard to cultivate, and its leaden skies, and into the midst of its fogs and frosts. After a course of plundering in Aquitania or in Provence, the Arabs of Spain and of Africa were eager to recross the Pyrenees or the Mediterranean, and regain their own lovely climate, and their life of easefulness that never palled. Furthermore, between Christians and Mussulmans the religious antipathy was profound. The Christian missionaries were not much given to carrying their pious zeal into the home of the Mussulman; and the Mussulmans were far less disposed than the pagans to become Christians. To preserve their conquests, the Arabs of Spain had to struggle against the refugee Goths in the Asturias; and Charlemagne, by extending those of the Franks to the Ebro, had given the Christian Goths a powerful alliance against the Spanish Mussulmans. For all these reasons, the invasions of the Saracens in the south of France did not threaten, as those of the Northmen did in the north, the security of the Gallo-Frankish monarchy, and the Gallo-Roman populations of the south were able to defend their national independence at the same time against the Saracens and the Franks. They did so successfully in the ninth and tenth centuries; and the French monarchy, which was being founded between the Loire and the Rhine, had thus for some time a breach in it, without ever suffering serious displacement.