to the 9th century BCE, eventually taking Sao form between the 11th and 4th centuries BCE, such that, by the end of the first millennium BCE, Sao presence was well established around Lake Chad and near the Chari River. The city-states of the Sao reached their apex sometime between the ninth and fifteenth centuries CE.

Although some scholars estimate that the Sao civilization south of Lake Chad lasted until the fourteenth or fifteenth century, the majority opinion is that it ceased to exist as a separate