The Etruscan city of Spina (VI - III century B.C.) and the city of Comacchio in its origins (VI - IX century A.D.) were ports and trading emporiums of great importance for the European trade routes (from the Mediterranean East to the other side of the Alps). With the 10th century AD. Comacchio declined in importance as a major commercial junction due to the main course of the Po River (12th century) deviating northwards, resulting in the modification of the road network, and the growing power of Venice, which attacked and destroyed it several times. In the late Middle Ages, Comacchio became part of the Duchy of the Este, themselves feudal lords of the Pope. The area remained important for its natural resources, in particular for the abundant fish stocks, which were exploited by renting them out to external agents, to the detriment of the wealth and well-being of the city.