Adamorobe Sign Language (AdaSL) is an indigenous sign language found in Adamorobe, a village in eastern Ghana, Africa. This village has an unusually high incidence of hereditary deafness, in which there are about 300 deaf and 900 hearing people (Nyst). As a result, this sign language naturally emerged. AdaSL, which is estimated to be 200 years old, is independent from the national Ghanaian Sign Language. Everyone speaks AdaSL that both deaf and hearing people enjoy full integration into the community.
Nyst, Victoria. "A descriptive analysis of Adamorobe Sign Language, Ghana." LOT Dissertation Series 151. Netherlands Graduate School of Linguistics. http://www.lotpublications.nl/index3.html