I agree - Ragnar Lothbrook was the King of Sweden and Denmark (and that is a main character of relevance that comes to mind), he was the son of the Swedish (svea) king Sigurd Hring, he would have been familiar with for example, the Viking town Birka in lake Mälaren - that could have been the centre of the tale together with other major viking towns all over Scandinavia, and even Hedeby in present-day northern Germany. It should have been played out in Scandinavia - with shorter stories on the UK, France (Paris), Constantinople, etc etc.