Beginning with the eleventh century many signs indicated a complete revival of trade, which had been nearly annihilated by the internecine struggles and the invasion of the Normans during the ninth century. At the end of the tenth century Flanders was already in touch with the Arab merchants trading in the Baltic; coins of the counts of Flanders are to be found in Denmark, Prussia, and Russia. The merchants of that time were traveling merchants, going from one town to another, and never remaining permanently in any one spot. All along the rivers wharves were established for discharging goods and wares, as well as winter quarters for the traders for the period during which the rivers were frozen. These were to be found at Valenciennes, Cambrai, Ghent on the Scheldt, Dinant, Huy, Liège, and Maestricht on the Meuse. Bruges became a central meeting-place for Flemish, Walloon, German, Frisian, and Anglo-Saxon merchants, and between the Scheldt and the Thames commercial intercourse was frequent. Little by little there grew up a special class who depended for a living on sale and purchase. A man became a merchant just as another became a knight, a priest, or a farmer. All those without land, the discontented “serfs” who succeeded in escaping from the domain to which they were attached, steadily augmented this early nucleus of the merchant class. The invasion of England by William the Conqueror (1066) and the large numbers of the Flemings who participated in it strengthened the economic ties between that country and Flanders, between London and Bruges. In Bruges[9] vessels from all parts of Europe were loaded with cargoes for London: wine from France and Germany, stone from Tournai, cloth of gold and groceries sent by the merchants of Lombardy, wool and linen cloths manufactured in Flanders. The prosperity of the Flemish trade attracted the representatives of European commerce; fairs and yearly markets were established at Thourout, Messines, Lille, Ypres, and Douai. Along with trade came the development of industry. On the Belgian coast the sheep-raising industry goes back as far as the early days of Roman occupation; woolen cloths were a special manufacture of the region. The more extensive the “polders”--the meadows wrested from the sea--became, the more the number of sheep raised on them increased, and consequently also the number of people connected with the wool industry. As trade developed the conditions of that industry, more and more people found occupation in the manufacture of woolen cloths. A special class of craftsmen was born. They deserted the countryside and settled down in the neighborhood of the merchants; trade and industry attracted each other. Flanders then became the seat of the cloth industry.