In the year 1086 the territories of Alfonso and other Christian sovereigns were invaded by a vast army of Almoravide Moors, who, sweeping over from Africa, menaced Central and Northern Spain. When he learned of their advance Alfonso was engaged in the siege of Saragossa, but in view of the danger which confronted him he joined his allies at Toledo and prepared to give battle to the invaders, who, numerous in themselves, had been reinforced by the Moors of the various Mohammedan states in Spain. Before leaving Toledo Alfonso was visited by one of those terrible visions of the night which, history tells us, have so often prophesied the fall of nations. It appeared to him that he was mounted on an elephant, and that beside him, on the flank of the great beast, was placed an atambore or Moorish drum, which he beat with his own hands. But the clamours which pealed forth from the instrument were so loud and terrifying that he instantly awoke in terror and amazement. At first he scoffed at the dream as nothing but a nightmare, but when it returned again and again on the succeeding nights of his stay at Toledo he began to feel that it must contain some element of awful warning. Night after night he awoke in great terror, drenched with perspiration, and with the echoes of the Eastern drum thundering in his ear, until at last, in great disquietude, he resolved to ask the advice of the learned men of his Court regarding what the vision might portend. With this object in view, he summoned to his presence the scholars and sages of his retinue, as well as the bishops and priests, and even the rabbis of the Jews who were his vassals, and who were more profoundly skilled in divination and the interpretation of dreams than any of his Christian subjects. When they had come before him, he related the substance of his dream, which he described very minutely, concluding his narration by saying: "That which most amazes and alarms me in this matter is the peculiarity of the elephant which I see in my visions, and which is an animal not reared in our country nor seen therein. In like manner, the atambore is not of the form and kind which we have in use among us, nor is that either to be seen in Spain. Wherefore do ye consider what these may portend, and give me the signification thereof without delay."