In some regions, pastoral elites were of partly Nilotic descent, while in others they may have derived mainly from the Bantu population (so theorized by the linguist David L. Schoenbrun from certain of those relatives of wealthy banana cultivators who were not eligible for inheritance). The latter had gradually adopted specialist pastoralism as a source of wealth in the area's rich grasslands. The earliest states may have been established between the 13th and 15th centuries by a group of pastoral rulers called the Chwezi. Legends depicted the Chwezi as supernatural beings, but their material remains at the archaeological sites of Bigo and Mubende have shown that they were human and perhaps among the ancestors of the modern Tutsi pastoralists of Rwanda and Burundi. During the 15th century, the Chwezi were displaced by a new Nilotic-speaking pastoral group called the Bito. The Chwezi appear to have moved south of present-day Uganda to establish kingdoms in northwest Tanzania, Rwanda, and Burundi.