Norse religion refers to the religious traditions of the Norsemen prior to the Christianization of Scandinavia, specifically during the Viking Age. It is a folk religion, which was not necessarily formalized nor categorized as a subset of Germanic paganism until it was described by outsiders who came into contact with native practitioners. It was the northern variation of the religion practiced in the lands inhabited by the Germanic tribes across most of Northern and Central Europe prior to Roman and Holy Roman incursions. Knowledge of Norse religion is mostly drawn from the results of archaeological field work, etymology and early written materials as it was largely a product of earlier people who did not have a written history.