Present-day Cameroon was first settled in the Neolithic Era. The longest continuous inhabitants are groups such as the Baka (Pygmies). From there, Bantu migrations into eastern, southern and central Africa are believed to have occurred about 2,000 years ago. The Sao culture arose around Lake Chad, c. 500 AD, and gave way to the Kanem and its successor state, the Bornu Empire. Kingdoms, fondoms, and chiefdoms arose in the west.