The Viking Age is characterized by expansion and emigration by Viking seafarers.

According to tradition, Harald Fairhair (Harald Hårfagre) unifies them into one in 872 after the Battle of Hafrsfjord in Stavanger, thus becoming the first king of a united Norway.

(The date of 872 may be somewhat arbitrary.

In fact, the actual date may be just prior to 900).Harald's realm is mainly a South Norwegian coastal state.

Harald Fairhair rules with a strong hand and, according to the sagas, many Norwegians leave the country to live in Iceland, the Faroe Islands, Greenland, and parts of Britain and Ireland.

The modern-day Irish cities of Dublin, Limerick and Waterford are founded by Norwegian (and Danish) settlers.

Norse traditions are slowly replaced by Christian ones in the 10th and 11th centuries.

This is largely attributed to the missionary kings Olav Tryggvasson and St. Olav.

Haakon the Good is Norway's first Christian king, in the mid-10th century, though his attempt to introduce the religion is rejected.

Born sometime in between 963–969, Olav Tryggvasson sets off raiding in England with 390 ships.

He attacks London during this raiding.

Arriving back in Norway in 995, Olav lands in Moster.

There he builds the first Christian church in Norway.

From Moster, Olav sails north to Trondheim, where he is acclaimed King of Norway by the Eyrathing in 995.