Angolan Chokwe People Idiophone (Thumb Piano): "Sanza"

In Chokwe communities of the southern savannah region of central Africa, in Angola, oral historians make political commentary while singing the praises of accomplished individuals. The music of thumb pianos and stringed instruments often accompanies their voices.

The instrument consists of a wooden board, often fitted with a gourd resonator, with attached staggered metal tines. It is played by holding the instrument in the hands and plucking the tines with the thumbs.
Source:
https://high.org/collection/thumb-piano-2/
https://en.wikipedia.org/wiki/Mbira