It is likely that the Foi first entered the Mubi Valley from the southwest, bringing domesticated sago with them. Although the Foi were briefly contacted along the southern reaches of their territory at different times by explorers moving inland from the Papuan Gulf coast, it was not until Ivan Champion first sighted Lake Kutubu in 1935 and consequently visited the lake on foot during his Bamu-Purari patrol that regular contact was established between the Foi and Europeans in the form of the patrol post at Lake Kutubu. The Unevangelized Fields Mission began activities at both Lake Kutubu and the middle Mubi Valley in 1951, and by the late 1960s the traditional religious life of the Foi had been largely superseded by Christianity. From 1950 the Foi were administered from various highlands patrol posts until the early 1970s, when a new administrative center was built and government health stations were reestablished in the Mubi Valley. Australian administrators introduced various European and other foreign vegetables to the area, including Singapore taro, pumpkins, chokos, Cavendish bananas, and pineapples. In 1988, large oil reserves were discovered west of Lake Kutubu in Fasu territory. The Foi of the upper Mubi Valley Traditionally traded and occasionally fought with their highlands neighbors to the north. They exported the reddish oil of the kara'o tree (Campnosperma brevipetiolata) and in return received pearl shells, pigs, and ax blades. The Foi of Lake Kutubu were rather more under the influence, because of their close ties with the intervening Fasu people, with the Bosavi complex to the west, and it appears as if the boys' homosexual initiation cult, the gisaro-kosa ceremonial complex, and other Bosavi cultural traits had moved eastward into Foi territory shortly before Champion's contact. In the last twenty years, the more populous and politically ascendant peoples of the highlands have exerted some amount of cultural hegemony over the Foi. The Foi have therefore experimented with the southern highlands pork-and-pearl-shell exchange in recent years. Relations with eastern and southern neighbors appear to have been more tenuous.