Neolithic settlements at Shum Laka and Abeke date from between 5000 and 4000 BC. From around 500 BC Bantu-speaking farmers originating in central Cameroon began migrating to the east and south and, over the next 2,000 years, dispersed across most of the African continent. The Sao civilization developed in the far north, close to Lake Chad, from around 600 AD. It developed ties with the Kanem kingdom, which for a time controlled trans-Saharan trade.