Another kind of industry was in process of development in Eastern Belgium, in the valley of the Upper Meuse. This was a mountainous region, filled with copper and tin mines along the banks of the river between Huy and Dinant. Here was developed a metal industry, whose products were shipped out on the river Meuse. After the tenth century the native mines were no longer sufficient for the needs of the country; the population of Huy and Dinant supplied its needs from the mines of Goslar in Germany. The products of the copper and tin industry were exported to France and England. Brabant, the central part of Belgium, remained for a long time purely agricultural. In the middle of the twelfth century, however, a highroad was constructed between Cologne and Bruges, passing through Maestricht, Saint-Trond, Léau, Louvain, Brussels, Alost, and Ghent. Trade now flowed, not only from south to north by the Scheldt and the Meuse, but also from east to west along the new commercial road. This remarkable development of trade and industry was mainly responsible for the origin and growth of the communes. Of course, for many centuries episcopal residences (_civitates_), castles and manors (_castra_), churches and monasteries had been centers of civilization and an attraction for the population of the neighborhood. And under the protection of their walls were grouped many wealthy villages. The latter, however, would probably never have developed into cities except for the presence of a colony of merchants and craftsmen. These colonies established themselves in neighborhoods where they could find favorable conditions for trading as well as protection for their commerce. Naturally, therefore, they settled in the vicinity of castles and convents (the castles affording military and the convents moral protection), at the confluence of two or more rivers, along a commercial highroad, in the curve of a gulf, or at the mouth of a stream. In this manner the cities of Bruges, Ghent, Brussels, Louvain, Liège, Malines, etc., were born, for it is an interesting point of Belgian history that nearly all the cities originated during the Middle Ages, very few of them dating back to the Roman times. Those colonies of merchants and craftsmen grouped together in professional and religious associations were called “guilds,” and introduced an entirely new spirit among the people of the growing town. The unfree population dependent upon the convent, the church, or the castle had no means of changing its conditions of life, bound as it was by the numerous ties of feudal and other obligations. But the traders had to secure for themselves a certain degree of liberty, safety, and autonomy. The feudal régime or the rules of the manor were intolerable to them. The operation of the system was too tyrannous; it acted too much as a restraint on private liberty and would have rendered the free development of commercial and industrial enterprises impossible.