Theory on immigration to Norway

Following studies in Iceland from 1825 to 1827, Rudolf Keyser was appointed as a docent at the Royal Frederick University in Christiania, Norway in 1828.

He later supplemented the theory with a series of lectures in literary studies, printed posthumously, under the name Nordmændenes Videnskabelighed og Literatur i Middelalderen.

He too based the theory partly on linguistic traits, and also stated that the two groups had different approaches to liberty versus hierarchy.

The Danish historian Christian Molbech dubbed Keyser and Munch's viewpoint as "The Norwegian Historical School".

A lecture held by Ludvig Kristensen Daa on a Scandinavian conference in 1868 has been called "the graveside speech for the immigration theory".