Until the twentieth century the Bedouin of the Sinai peninsula and the Negev desert were no less dependent upon knowledge of the heavenly bodies than their nomadic ancestors of countless generations in the Arabian peninsula. The stars were as vital to a Bedouin trying to find his way in almost featureless stretches of the desert waste as they were to a sailor navigating the open sea. Moreover, the Bedouin needed stable indications of the seasons of the year so that they could regulate the annual activities necessary for agriculture and livestock raising; the only calendar they knew was the Muslim lunar calendar, the months of which rotate among the seasons of the year, at times appearing in the winter, at others in the spring, summer, or autumn. They found these indications in the positions of the stars. Finally, their preoccupation with the heavenly bodies and their nightly exposure to starry skies naturally led the inhabitants of the desert, like many other peoples, to find, in the movements of the stars, explanations for the natural disasters to which they were always so vulnerable.