The enterprising spirit of the Arabs which induced them to extend their conquests to all accessible points on the Mediterranean early suggested the occupation of the largest islands of that sea, whose importance as naval stations whence invading armies might be transported into Europe, and as bases for the equipment of piratical undertakings, was fully recognized by every nation. The Balearic Isles were a dependency of the khalifate of Cordova. They paid tribute to its sovereigns like other provinces of the empire, furnished troops for its armies, participated largely in its civilization, and, fortunate in their isolation, survived for nearly two centuries its overthrow. Sardinia, invaded by Musa in the first years of the eighth century, was never completely subjugated by the Saracens. The mountainous and barren interior of that island, sparsely inhabited by a barbarous and poverty-stricken peasantry, repelled them from a conquest whose doubtful advantages could not possibly compensate for the toil and danger necessary to secure it, and the coast with its harbors seemed the only territory worthy of their attention. For the space of seventy years the Moors retained a precarious foothold on the shores of that island, and the possession of a few insignificant seaports was disputed by the Franks and Italians with a pertinacity not unworthy of a contest involving the fate of an extensive kingdom. In 722 the Saracens, having become familiar with the extensive traffic in relics carried on by the Catholic clergy and determined to turn to their own profit the superstitious credulity of the devout, entered into negotiations with Liutprand, King of the Lombards, for the sale of the body of St. Augustine, which had reposed in peace for two hundred years in the metropolitan church of Cagliari. The transaction was betrayed by the arrival of the messengers of Liutprand, and the people, incited by the monks, rose in revolt. An unsuccessful attempt was made to rescue the ashes of the saint, the Arab garrison was called out to quell the tumult, and seven monks paid the extreme penalty of their zeal, and perhaps not wholly disinterested piety. In view of the precious character of these mementos and of the difficulties attending their transfer, the Arabs exacted, in addition to the price already agreed upon, the payment of three pounds of gold and twelve of silver; an amount which indicates the immense value of the original ransom. The grief of the devout inhabitants of Cagliari on account of their loss was somewhat alleviated by the remembrance that the vestments which had been torn from the bones of the saint in the struggle still remained in their hands, and the innumerable miracles wrought by these tattered garments, confirmed by the highest ecclesiastical authority, long attested the celestial influence and supernatural virtues possessed by the sacred relics of the deceased Bishop of Hippo.