The term Saracens is of doubtful origin. At first it was applied by the Greeks and Romans to the nomad Arabs, who harassed the frontier of the empire from Egypt to the Euphrates; but afterwards, during the middle ages, to the Moslems in general, the Saracens having been the earliest and most enthusiastic converts of Islam. In the seventh century the Saracens conquered Arabia, North Africa, and part of Asia; and in the eighth century they conquered Spain (711), but their progress in France was stopped by their defeat by Charles Martel, at Tours (732). The great caliphate of Bagdad, founded in 764, fell before the assaults of the Tartars in 1277; the great caliphate of Cordova, founded in 756, endured till 1031, when it was broken up into smaller governments, the last of which, the kingdom of Granada, fell before Ferdinand of Spain in 1492. Like the Normans, the Saracens were a people of great enterprise and rare adaptability, and quickly surpassed their teachers in all the arts which embellish life.