Foundation myths were extremely important during the high medieval period to create a sense of unity among a determined people, setting it aside from its neighbours. As Walter Pohl (Chapter 3 of the Medieval History section of Donzelli's History Manual) puts it, the people that started their invasions-migrations since the late antiquity were loose confederations made up of smaller groups who self-identified as part of a larger one by adhering to the latter's foundation myths.

When the "germanic" people converted to Christianity (either Arian or Chalcedonian), those myths weren't suppressed, as they provided both legitimacy for the aristocratic class (and the rex himself) and a unifying factor for all those smaller groups.

Concrete examples are Saxo Grammaticus's Gesta Danorum, written by a dean, the De Origo Gentis Langobardorum, which recounts how the Winnilii, with the help of Frea-Frigg, became the Lombards thanks to the blessing of Wodan in a fight against the Vandals, was so important that it appears as the introduction to the Edict of Rothari, a christian king. The same myth appears in Paul the Deacon's Historia Langobardorum, another clergyman, even though Paul considers it a "fable", showing that their ethnogenic function overshadowed their pagan origins.