There had been pirates in the Mediterranean long before the Turks took up the trade; indeed, ever since boats were built their capabilities for plunder must have been realized. The filibustering expedition of Jason and the loot of the Golden Fleece is an early instance, and the Greeks at all times have distinguished themselves by acting up to Jason's example by sea and land. The Moslems, however, were some time in accustoming themselves to the perils of the deep. At first they marvelled greatly at "those that go down to the sea in ships, and have their business in great waters," but they did not hasten to follow them. In the early days of the conquest of Egypt the Khalif 'Omar wrote to his general and asked him what the sea was like, to which 'Amr made answer: "The Sea is a huge beast which silly folk ride like worms on logs;" whereupon, much distressed, the prudent Khalif gave orders that no Moslem should voyage on so unruly an element without his leave. But it soon became clear that if the Moslems were to hold their own with their neighbours (still more if they meant to hold their neighbours' own) they must learn how to navigate; and accordingly, in the first century of the Hijra, we find the Khalif 'Abd-el-Melik instructing his lieutenant in Africa to use Tunis as an arsenal and dockyard, and there to collect a fleet. From that time forward the Mohammedan rulers of the Barbary coast were never long without ships of some sort. The Aghlabī princes sailed forth from Tunis, and took Sicily, Sardinia, and Corsica. The Fātimī Khalifs waged war with the navies of 'Abd-er-Rahmān, the Great Khalif of Cordova, at a strength of two hundred vessels a side. The Almohades possessed a large and capacious fleet, in which they transported their armies to Spain, and their successors in North Africa, though less powerful, were generally able to keep up a number of vessels for offensive as well as commercial purposes. During the later Middle Ages the relations between the rulers of the Barbary coast--the kings of Tunis, Tilimsān, Fez, &c.--and the trading nations of Christendom were amicable and just. Treaties show that both parties agreed in denouncing and (so far as they could) suppressing piracy and encouraging mutual commerce. It was not till the beginning of the sixteenth century that a change came over these peaceful conditions, and the way it happened was this.