The Norse sagas describe him as successful in extending his realm over the Baltic Sea, but unsuccessful in his attempts of westward expansion.
[1] However, Saxo Grammaticus identifies Erik Weatherhat with another figure, a son of the legendary Viking Ragnar Lodbrok.
[2] He is given as the son of Anund Uppsale in the Hervarar saga (13th century): However, the Eric who was contemporary with Harald Fairhair is called Eymundsson by Snorri Sturluson.
In the saga of Olaf Haraldsson, Thorgny Lawspeaker relates: In Harald Fairhair's saga, Snorri Sturluson relates that Eric also wanted to extend Sweden westwards and to make a kingdom for himself as large as that of the Swedish king Sigurd Hring and his son Ragnar Lodbrok (i.e. Raumarike, Vingulmark and Westfold all the way to the island of Grenmar).
Thus he conquered Värmland and all the land south of Svinesund (modern Bohuslän) and claimed the shores of Viken as his own, naming it all West Götaland.
When King Harald Fairhair arrived at Tønsberg (in Viken, and at the time a trading town) from Trondheim, he learnt of this and became very angry.
[9] When the winter arrived, Harald learnt that the Swedish king was in Värmland, after which he crossed the Ed forest and ordered the people to arrange feasts for him and his entourage.
The Norwegian king found himself in a hall with new gilded vessels carved with figures and shining like glass, full of the best liquor.
When Eric and his men became aware that they were pursued, they rode as hard as they could until they had reached the wood that divided Värmland and Götaland.
[12] The only possibly contemporary sources for the war are three scaldic verses said to be composed by King Harald's skald Þorbjörn Hornklofi.
The historian Curt Weibull has characterised Eric as historically problematic, and doubted that the Swedes had anything to do with Värmland or West Götaland in the late 9th century.
[13] A late 9th-century geographical account preserved in an Anglo-Saxon manuscript, by Ohthere of Hålogaland, vaguely says that Norway borders "to Sweoland at the other side of the mountains, until the southern part of the country, and far up to the north".
Another account in the same manuscript, by Wulfstan of Hedeby, says that Blekinge, Möre, Öland and Gotland belonged to the Swedes (hyrað to Sweon).
Later on, Harald's trustee Hauk Håbrok went to Holmgard in Kievan Rus' to make purchases but had an adventurous confrontation with two champions of Eric who stayed there.