The banjo is a four to five (or occasionally six) stringed instrument with a thin membrane stretched over a frame or cavity as a resonator. The membrane is typically a piece of animal skin or plastic, and the frame is typically circular.
The banjo was invented and widely used in ancient Mauritania, the Sahel and the Coast of Guinea.
This instrument is similar to the North African Moorish guitarro. The Moors of West Africa, the Mauritanians, and the African slaves who were sent to the Americas during the Trans-Atlantic Slave Trade re-created the banjo into what we know today as the guitar.
According to Thomas Jefferson, "The instrument proper to them (i.e. the slaves) is the Banjar [Banjo], which they brought hither from Africa."
Banjo was widely used in American folk music until the Depression of 1929, when historians remarked that its happy notes were replaced by the more sombre notes of the guitar.
*culled from www.infoboxdaily.com