At the end of the 8th century Scandinavia had hardly more than two million inhabitants. But from the beginning of the 9th century its population began to increase significantly. There were several reasons for this: on the one hand the climate was getting better; it became warmer and thus harvests were becoming more abundant, the people better fed and stronger. The mortality rate of the old and infants during winter had also decreased. As the years went by, unoccupied Scandinavian territory became harder and harder to find.

        To these demographic factors certain features of Viking life must be added: such as polygamy, which produced a large number of children, the obligation for young men to seek their fortune elsewhere, and Viking laws, which used exile as a punishment for criminals. There were, therefore, many reasons to take to the sea and chance one's arm beyond one's native shores.

        The Vikings were a bold people, who welcomed risks and who had a passion for voyaging abroad. In the 11th century, not far from their coasts, a great trade route was opening up, passing through the ports of Frisia (now Holland) and the Rhine valley. This route became the crossroads of all commercial exchange in northern Europe.

        The Vikings, attracted by all the goods which were beginning to pass so close to them, took more and more interest in the trade. Eventually this interest led to piracy and plunder.