Define Viking. Long-haired and wild-eyed, you say? Far-ranging, bloody-knuckle brutal?

OK, that's a fair description of Jared Allen of the Minnesota Vikings.

And what about those "What's in your wallet?" commercials, where "the boys" talk loud and break things and look sheepish when they're scolded?

The first Vikings had image problems, too, much of that because of bad press: the scribblings of outraged monks. In "The Vikings," Robert Ferguson uses his familiarity with the sagas, Eddas and Skaldic poetry to refine our perceptions.

To some extent, 19th-century historians in Scandinavia reconstructed a Viking age "for ideological reasons," Ferguson notes. "Each nation was, for differing reasons, in need of a lost golden age of greatness." Denmark had been beaten up by Prussia in 1864, while Sweden still grieved losing Finland to Russia earlier in the century. Norway, hankering for independence from Sweden, found romance and glory in the Norwegian Viking colonization of Iceland and Greenland and the brief settlement in 1000 -- half a millenium before Columbus -- in Newfoundland.

The Vikings were "noble savages," which rationalized their violence, while their eventual acceptance of Christianity justified the equally brutal conversion campaigns of opponents. In more recent times, the tendency has been to depict the Vikings as more than marauders. The exhibition of more than 500 objects from the Viking world assembled by the British Museum -- with a lengthy run at the Minneapolis Institute of Arts in 1981 -- showed them as farmers, artists, poets and traders (if primarily of the smash-and-grab variety).

But the revisionism may have gone too far, Ferguson writes, so he seeks "to restore the violence to the Viking Age, and to try to show why our understanding is incomplete without it."

He dates the Viking Age from about 790, when northern heathens first swarmed onto the shores of western Europe, to 1100, when Christianity had taken hold in all the northern countries. His sources include few written records, and most of those from outside Scandinavia. The discovery of the richly furnished Oseberg Viking ship in Norway in 1904 provided many clues to faith, art, crafts and personal life, but Viking history remains largely a matter of informed conjecture.

We see this formidable land, home and sortie point, as if peering through mist, unsure of shadow or shape, squinting as we are through a thousand years.

The strength (and challenge) of Ferguson's work is that despite the great gaps in what we know, it is thorough, a marshaling of evidence argued over for centuries. As such, it isn't always an easy read. Who can keep track of so many obscure Eriks and Ragnvalds plundering places with names long forgotten?

But we are rewarded with thoughtful insights and with spirited tales of Sweyn Forkbeard and Harold Bluetooth, of Ingvar the Far-Traveled, who pillaged along the shores of the Caspian Sea, and Ivar the Boneless, who despite being carried on a stretcher conquered York. We sail a thousand years ago in dragon-headed ships to the Arctic and to North Africa, deep into Russia and west to Iceland, Greenland and America, and ponder what our Viking name would be.

Chuck Haga, a longtime reporter for the Star Tribune, now lives and writes in Grand Forks, N.D.