The Vikings were Scandinavian explorers, warriors, merchants, and pirates who raided and colonized wide areas of Europe from the late 8th to the early 11th century. Their travels took them as far east as Constantinople and the Volga River in Russia, and as far west as Iceland, Greenland, and Newfoundland. This period of Viking expansion is known as the Viking Age, and forms a major part of the medieval history of Scandinavia, Britain, Ireland and the rest of Europe in general.
American lawyer Allister Park found himself in an alternatetimeline where the people of "New Belfast," a city on the site of New York, spoke a semi-Scandinavian language. He found out that in this timeline, the Vikings (together with some Irish people) colonized North America and eventually established a nation-state, in some ways similar to and in others very different from the United States Park knew.
A major difference was that, because the Scandinavian settlers had been far fewer and had far less highly developed technology than the European settlers of Park's timeline, the Skraelings (Native Americans) were eventually able to catch up and stand up to them.
As a result, the nation established by the Vikings' descendants took up only part of North America and occasionally fought wars with the independent Skraeling nations to its west, which were its equals militarily. It was also faced with the major political issue of whether or not to grant equal rights to the considerable Skraeling population within its own borders, treated as second-class citizens for centuries.
There was no black minority, since the Vikings had European slaves rather than African ones, and once emancipated the descendants of these slaves assimilated into the general population.