In 1974 Barth moved to Oslo, where he became professor of social anthropology and the head of the city's Museum of Cultural History. During this period, anthropology was changing. Marxism and interpretive approaches were becoming more central, while Barth's focus on strategy and choice was being taken up by economics and related disciplines. Barth shifted to studying meaning and ritual as developed in ethnic groups, and conducted research in Papua New Guinea, where he conducted fieldwork with the Baktaman. He published several works from these studies, namely the "Ritual and Knowledge among the Baktaman of New Guinea" (1975). He also continued studies in the Middle East, conducting fieldwork in Oman with his wife Unni Wikan. This resulted in his 1983 volume "Sohar: Culture and Society in an Omani Town".