Regional scholars have adopted the linguistic designation Mountain Ok to refer to the culturally related peoples living in and around the Sepik River source basin of Ifitaman. These related peoples include the Telefolmin and Atbalmin, southern neighbors of the Miyanmin and their traditional enemies. The northern frontier contacts groups such as the Iwam and Abau who are speakers of Upper Sepik languages. The indirect evidence of forest burning in Ifitaman suggests the presence of people in the Mountain Ok area at least 17,000-15,000 years ago with agriculture appearing in the Region about 3,500 years ago. The linguistic separation of the major Mountain Ok groups may have occurred between 2,000 and 3,000 years ago. Mountain Ok groups share the belief that they were founded by an ancestress named Afek and that their separate existence is due to the travels of Afek or her sisters. The Miyanmin attribute their origin to one of these sisters. The most recent expansion and large-scale movement in the region began some 300 years ago. The Mountain Ok peoples were discovered by Richard Thurnwald and the German Sepik River expedition of 1912-1914. The expedition may have made visual contact with Miyanmin in the May Valley and the western Thurnwalds in 1913. This pattern of fleeting contact was sustained through subsequent visits by Westerners between 1927 and the 1950s when Systematic pacification was initiated by Australian colonial authorities. This coincided with the heavy impact of introduced diseases that continued through the late 1960s. Heavy fighting between the Miyanmin and neighboring groups in the 1950s and 1960s resulted in court trials and mass jailings. In response, several Miyanmin groups in the eastern Thurnwalds began to develop a local modernization plan and mass conversion to Christianity even before missionaries entered the area directly. The plan, which continues to evolve, includes the construction of bush airstrips as centers for education, health care, and commerce. The movement has now extended to many other groups. Today, most men have worked as laborers elsewhere in Papua New Guinea. A number of young people have attended high school or mission institutions, some have received vocational training in health care and education, and one is in university.