Barcelona’s post-Roman history was full of οverturns. The control of the Visigoths over the region lasted for almost 300 years and their rule was followed by that of the Moors, who formed a frontier-state between the Islamic al-Andalus and the Frankish Kingdom. The real turning point for the city’s history came in 1137, with the marriage of the city’s Count Ramon Berenguer IV with the daughter of the King of Aragon, Princess Petronilla. The union of the County of Barcelona and the Kingdom of Aragon created the Crown of Aragon and a new age of plenty began for Barcelona. From the 13th to the 15th century, it evolved into a strategic port-city and a financial and political centre of the Mediterranean West.