About half of the people in Papua New Guinea practise ancient religious beliefs that include rituals celebrating ancestors and spirits. This spirit house, in which no women are allowed, is typical of a longhouse serving one or more villages on the Sepik River. Before entering the spirit house, boys, upon reaching a certain age, must be initiated into manhood. The Ma, Namie, Sawos, Chambri, and Iatmal are among the nations who live along the Sepik, which is located in the country’s northern lowlands.