Sigurd Erixon, the key figure in Swedish ethnology, carried out his work during the first part of the twentieth century. His abundant research dealt mostly with the oldest strata of living popular tradition. In other words, it focused on that part of the historical epoch to which access was still available through oral testimony. Along with other documentary sources, his work thus served as the basis for a mapping of pre-industrial popular culture in Sweden. S. Erixon and his school dominated Swedish ethnology up to the 1960s, when a paradigm shift caused ethnologists to turn their interests to the study of local communities and to participational observation.