In the ninth century, Vikings carried out raids on the Christian north and Muslim south of the Iberian peninsula (modern Spain and Portugal), going on to attack North Africa, southern Francia and Italy and perhaps sailing as far as Byzantium. A century later, Vikings killed a bishop of Santiago de Compostela and harried the coasts of al-Andalus. Most of the raids after this date were small in scale, but several heroes of the Old Norse sagas were said to have raided in the peninsula.

These Vikings have been only a footnote to the history of the Viking Age. Many stories about their...