The Viking Age in Norway began with the raid on Lindisfarne in 793, marking the start of Scandinavian expansion through raids, trade, and colonization. The development of the longship and advanced navigation enabled Norwegians to travel across Europe, raiding and settling in areas such as Ireland, Scotland, Iceland, Greenland, and the North Atlantic islands like Shetland, Orkney, and the Faroe Islands. Norwegian Vikings were well-equipped, skilled in warfare, and often sought gold, silver, and thralls (slaves) during their raids.
The lack of arable land in Western Norway prompted Norwegians to explore and colonize sparsely populated regions, establishing the Kingdom of the Isles in the Hebrides and founding cities like Dublin in Ireland around 800. However, by 900, Norwegian Vikings were driven out of Ireland by Gaelic kings.
Domestically, the mid-9th century saw intense power struggles among the petty kingdoms of Norway. Harald Fairhair, allied with the Earls of Lade, began the process of unifying Norway after his victory at the Battle of Hafrsfjord (circa 870–900). Harald established a basic state administration, setting stewards over important estates to consolidate his rule, laying the groundwork for a more centralized Norwegian kingdom.