4 MOHAMMEDAN INVASION The only serious invasion of the Arabs was by land from Mekran, the most eastern province of the caliphate on the Persian coast, whose Mohammedan governors frequently came to blows with the Indians across the frontier, where no natural barrier intervened. The invasion was belated, compared with the other cam- paigns, for the caliphs' hands were full of more press- ing affairs. The tremendous successes of the first sweep of Arab conquest are apt to blind us to the tedious and toilsome progress of their arms in all but the earliest campaigns. No doubt their triumph over the degenerate empires of Kome and Persia was comparatively swift. Five years sufficed for the subjugation of Syria, seven more saw Persia at their feet, and two were enough for the conquest of all Egypt. But when the Arabs were opposed by tribes as untamed and warlike as them- selves, their advance was slow and difficult, and every mile was obstinately disputed. Carthage, for example, was all but reached within a few years of the conquest of Egypt, but it did not actually fall for nearly half a century, and the vigorous resistance of the Berber tribes delayed the progress of the Moslems in Africa till the close of the seventh century. It was the same in the East. While Persia was speedily overcome as far as the river Oxus, it was not till the first decade of the eighth century, almost two hundred years later, that the country beyond its banks was added to the settled provinces of the caliphate. The Arabs were too few for all the work they attempted in widely separated lands, and up to 700 A. D. they had quite enough to do
