According to the traditional view, after Harald Fairhair first unified the kingdom, Norway was inherited by his agnatic (male) descendants.

However, in the first centuries after Harald Fairhair, there were several periods during which the country was effectively ruled not by a king but by one of the Jarls of Lade, (Old Norse Hlaðir), from the northern part of Norway.

Also, although Harald Fairhair's kingdom was the kernel of a unified Norway, it was still small and his power centre was in Vestfold, in the south.

[6][7] One motive would be to increase the legitimacy of rulers by giving them a clear royal ancestry dating back to the foundation of the kingdom.

Joan Turville-Petre explored the relationship between them and argued that the original aims were to establish a framework of regnal years for dating and to connect Icelandic chieftains to them,[8] and that the Vestfold origin of the dynasty was deliberately altered and they were connected to the Swedish Ynglings rather than the Skjǫldungs to fit Icelandic tradition.

[9] Claus Krag argued that an important motive was to establish a hereditary claim to Viken, the region around Oslo, because the area had been paying taxes to the King of Denmark.

However, Viken and its region of Norway, Vestfold, were not parts of Harald I's dominions but subject to the Danish kings at the time, making this connection dubious.

Further, the future king Olaf is said to have been born posthumously to a mother who had taken refuge in the Orkney Islands, yet the age assigned him in other sources would place his birth years after the date attributed to the death of his father.

The Heimskringla then relates that he was enslaved in Estonia as a three-year-old, only to tell his true parentage to the man who discovered him there and freed him six years later.

The reliability of these two claims depends on the credibility of the Icelandic accounts (in particular Heimskringla) and the sources used to compile them, and if deemed unreliable, their reigns would represent distinct dynasties from that of Fairhair.

Harald IV arrived in Norway from his native Ireland and claimed to be the natural son of Magnus III, sired during the latter's Irish expedition.

His claim seems, from historical sources, to be based on tales told by his Irish mother and family circle during his youth.

The most seriously discredited alleged scion, practically regarded as an impostor by many modern academics,[citation needed] was Sverre I, who arrived in Norway from his native Faroe Islands, took up leadership in the embattled and heirless Birkebeiner party of the civil war, and claimed to be the natural son of Sigurd II by Gunhild, Sverre's attested mother.