The nomad Tatar, or so-called Scythian populations, have been already slightly noticed; the rapidity with which they spread their arms over Asia having been a matter of surprise to every historian who has written on the subject. About the time of Mahmud of Ghazna, after having overrun the West of India, an important section of them settled in great force in Asia Minor. Opposed to the Greeks and their religion, they became the most powerful enemies the eastern Roman empire had yet encountered; and their occupation of the Holy Land, with their conquest of Jerusalem, led to conflicts with the Greeks only less terrible than had been the earlier wars between the Saracens and the nations of the West. Their ignorance of navigation alone deferred for a time the fall of the eastern empire, though internally weak and decrepid, chiefly owing to the blow it received during the Crusades, and from which it had never recovered.[363] The first Crusade, made about twenty years after the conquest of Jerusalem, had for its object the recovery of the Holy City from the infidel. To replace the Cross in Palestine, where the Crescent had been impiously raised, was a duty the whole of Christendom considered itself bound to accomplish. But the Christians in their enthusiasm undertook a task as wild as it was disastrous, and one, too, so miserably planned, that three hundred thousand of the first Crusaders lost their lives, either by fatigue and hunger or by disease and the weapons of the Saracens, before they rescued a single city from their grasp. [Sidenote: A.D. 1147.] [Sidenote: Siege of Acre, A.D. 1189.] [Sidenote: Armistice, A.D. 1192.]