The Songye migrated during the 16th century from the Shaba area to the left bank of the Lualaba River, which is characterized by savannah and forest covered plateau, in an area of what is now known as the Democratic Republic of the Congo. The 150,000 Songye people are governed by a central chief, the Yakitenge, whose role demands that he obey special restrictive laws such as not showing grief, not drinking in public, and not shaking hands with men. The secret society known as Bwadi Bwa Kifwebe counterbalances his power. The word Kifwebe means, literally, "mask" in the Songye language. A Kifwebe mask is typically covered with linear incisions, a square protruding mouth, and a linear nose set between globular pierced eyes. This particular mask is masculine, as indicated by the carved central crest. The size of the crest determines the magical power of the mask. During initiation, circumcision, or funeral cermonies, a dancer will wear the mask and his body will be covered with straw. The dancer who wears the male mask will display aggressive and uncontrolled behavior with the aim of encouraging social conformity. -Bacquart