Dorestad was the largest of what are (and were then) called emporia. An emporium was founded by a king or high ruler with the express purpose of facilitating the trade and production of high-status goods. Emporia were always located on large rivers or harbors, in order to enable wares from the interior to be exported, and provide an exceptional port for merchandise to come from abroad. They were very much working class towns, and in general the nobility and the religious avoided making the towns centers of non-economic activity.
Dorestad was located at the junction of the Rhine and Lek rivers, in what is today the Netherlands, and what was then called Frisia. In addition to the obvious advantages that a port on the Rhine provided, there was an old Roman fortress near the site that probably contributed some feeling of security. One disadvantage of Dorestad was that it was located very close to the undefined but fiercely contested border between Frisia and Austrasia. As a result the town changed rulers fairly frequently after its founding in the early seventh century.