regarding the origins of the banjo:

Here's a link to a YouTube series called "THROW DOWN YOUR HEART", about Bela Fleck's trip to Africa. In the first of the series he states that the banjo's origin was Africa, and there is a clip of such an instrument being played.

Other clips show a variety of instruments used on the continent.

Interesting viewing if you have about an hour to watch all the clips. Each clip is about 5 minutes, and the very first one shows the banjo's predecessor.

https://www.youtube.com/watch?v=WDCxaQhhL0A