The urbanization which had begun in the ninth century continued during the tenth century, despite the Viking raids in the late ninth century, and reached its first peak in the eleventh century. That process can be divided into four phases and is visible in as many groups of cities, at least within what were then the most urbanized regions in the area between the Somme and the Meuse, namely the Meuse and the Scheldt valleys and the North Sea and Channel coast.

First, there was the expansion of the urbanized area from several nuclei which had begun to display signs of an urban character back in the ninth century: this was primarily the case in Ghent, even in the first half of the tenth century, in the Meuse Valley – particularly in Liège – in the second half of the tenth century, and in the old ecclesiastical centres of Arras, Tournai and Cambrai.

Second, in the course of the tenth century new urban settlements emerged in the county of Flanders, namely in Saint-Omer and in Douai. Though older, Bruges was in a sense part of this group.

Third, around the year 1000, new trade settlements grew up along the River Scheldt in Antwerp, Ename and Valenciennes, near castles erected on the right bank by the German emperor at the end of the tenth century to protect the border with the county of Flanders which had been provided by the River Scheldt since 925. At the beginning of the eleventh century a castle was built in Oudenaarde, immediately opposite Ename on the left bank, then part of the county of Flanders, and subsequently a trade settlement emerged at its feet.