 Since iron was a precious commodity, and iron smelting required technical knowledge, it was jealously guarded, resulting in a number of clans being subject to ironsmiths.The central chiefdom, Milanzi (""the eternal village""), was headed by a dynasty of ironsmiths, which exchanged its products for woven cloth.These clans and dynasties were later taken over by an even newer immigrant group, the Twa, possibly the Tutsi from the north, who were organized as a single clan and dominated others by force and cunning.