At the close of his 1962 work on the Vikings, Peter Sawyer reminded readers that every historical period is "the subjective creation of observers." This was especially true of the Viking Age, which emerges in many ways imperceptibly from the Migration Period. As Sawyer pointed out, for contemporaries "it began when the men of the West first became aware of the strangers of the North who came in search of land, wealth, and glory. It ended when they were no longer strangers." Subsequent generations, especially in Norden or in areas where significant numbers of Nordic immigrants or their descendants can be found, have repeatedly revisited, reinvented, or amplified the achievements of this period. Unquestionably, the years between about 800 and 1100 form an important unit in Norden's history. It is the prehistoric period that is the best known and most written about. Both accurate and fanciful accounts abound and are parts of the national canon of Nordic history. Exaggeration aside, this period does stand out as one of the most important extended moments in all of Scandinavian history--at least from the Nordic perspective. (Most general European histories devote very little space to the Vikings and usually treat them as nuisances and not real contributors to Europe's development.) Spanning nearly three centuries, the Viking Age was, in many ways, the final phase in the Migration Period and the time when Scandinavia made some lasting contributions to the general history of Europe in the Middle Ages. It was then that people from the region moved out to settle unoccupied places (including Iceland and the Faeroe Islands in the ninth century, and Greenland at the close of the tenth century), to trade, attack, plunder, intermingle with, and rule over peoples in already settled areas (especially in parts of the British Isles from 793), and to create and maintain a commercial world that reached from Greenland to Asia.

Although the scale of their impact and the long-term or lasting importance of the Vikings in European history are debatable, the vitality and richness of this period from the Nordic perspective are not. The abilities and achievements of relatively small groups of people are truly remarkable–seen through the prism of either their external or their internal activities. People from what is now east-central Sweden established trade and production centers on the island of Helgo and at Birka (on Bjorko) in Lake Malar, at several sites on Gotland and along the south Baltic shores, and in western Russia. At the same time, people from what is now Denmark and Norway maintained similar centers at Hedeby (near the present-day town of Slesvig in northwest Germany), Kaupang near Oslo, and probably near the present-day south Swedish community of Uppakra. These thriving towns served as commercial and production centers in a trade world that reached east down the Volga and Dnieper rivers, crossed northern Europe, and extended west to Greenland and beyond. Along this arc flowed goods from Asia, the Byzantine Empire, the Islamic Mideast, the Baltic, Europe and the British Isles, the Atlantic islands, and even North America. Simultaneously, Norse peoples from what were emerging as Denmark and Norway raided the British Isles and the Frankish kingdom, conquered and established dominance over part of England (the Danelaw), discovered and settled the islands of the north Atlantic, and reached at least as far west as today's L'Anse-aux-Meadows on the tip of northern Newfoundland. In Scandinavia the same period witnessed the continued coalescence of the early Danish, Norwegian, and Swedish monarchies from the cauldrons of tribal localisms, as well as the founding of the Icelandic, Faeroese, and Greenland republics. At the same time a variety of ancient local and regional legal systems and representative institutions remained vital. It was also an era of achievement in artistic and craft production (be it original, copied, or a blending of the two) in wood, metal, textiles, and boat construction that rivaled or surpassed the rest of Europe.

All these developments were possible and occurred because of a combination of Nordic and European factors. Among the former were the boat building and maritime skills of the Scandinavians, which gave them a temporary advantage over their neighbors; a polytheistic religion that emphasized conflict, daring, and reputation; population growth that put pressure on the existing land bases in some areas; and discontent with the developing political centralization. Among the European factors were the relative weakness or complete absence of political organization and defenses in areas where the Vikings were most successful, commercial opportunities, the availability of trade resources (often in the form of the riches of the Church), and the attractiveness of land for settlement. . . .

The apparent magic that the Viking Age holds for the people of Norden and for many of Scandinavian descent is hardly surprising. As art historian Brian Magnusson has written, to understand its enduring character, "one need only walk along a country lane in Denmark, Norway, or Sweden to experience physical testimony to Viking culture. Stately mounds, ship-settings, communal grave fields with their stone monuments and runestones, refuge sites, and occasional house foundations are all observable and, though mute and alien in our modern world, evoke an immediacy which tantalizes the imagination."