Physiological and cultural evidence suggest that the Kaluli are more closely related to lowland Papuan cultural groups than to those of the nearby highlands, but there is no hard evidence to suggest that they originated anywhere outside of the general territory that they currently occupy. Early trade relations and cultural borrowings appear to have been predominantly with the peoples to their north and west. Throughout their existence, the Kaluli have been moving very gradually eastward, away from established settlement areas, moving ever more deeply into the virgin forests. Some of this movement may be attributed to a need to seek fresh garden lands, but it may also be explained in part as a defensive response to the expansionist pressures of the Beami and Etoro, traditional Kaluli enemies who live to the west and northwest of Kaluli territory. Warfare and raiding were common on the plateau, but there were longstanding trade relations between the Kaluli and certain of the other plateau groups, particularly with the Sonia to the west and the Huli of the Papuan highlands. First European contact on the plateau occurred in 1935, bringing with it the introduction of new goods to the regional trade network—most significantly, steel axes and knives. World War II brought a temporary halt to Australian government exploration of the plateau, which only recommenced in 1953. At this time, there began more frequent though still irregular contacts with Australian administrators and more direct interventions into the lives of the plateau peoples. Raiding and cannibalism were outlawed by 1960, and in 1964 missionaries built an airstrip near Kaluli territory to serve two mission stations established nearby.