Weren't the Vikings from both Norway and Sweden? Those countries didn't exist as separate states back then. My forefathers were Vikings who went to Ireland via Normandy.
It appears the good Vikings, who brought civilization, were from Norway, and the bad Vikings, who brought burning and pillaging, were from Sweden.
This year, Norway is celebrating its 100th anniversary of independence from its older cousins, the Swedes, who had dominated it since 1815.
I believe even the U.S. Post Office is issuing a special commemorative stamp to mark the event.
I am still ploughing through biographies--real books, not internet sites--of kings of Norway (kindly suggested by Eurotwit, and his advice enthusiastically heeded), but it appears that from circa 1340 until 1815, Norway had been owned by their elder brothers, the Danes.
Why all this happened, well, I am not back that far yet.