In the 'Ragtime Era' of the early 1900's, the instrument companies made their money with acoustic instruments. Guitars were not that prevalent, nor were they completely nailed down design-wise. This is where you see the strange birds like the 'harp' guitars.
However, banjos were a big deal, and mandolins to a lesser extent. Mandolins are essentially a fretted violin with paired strings, and this was a time for banjos before the five-string we generally think of these days. They were marketed as families of instruments, with the four voice ranges like the violin family.
So you'd see acoustic/choral groups with mandolin, mandola, mandocello, and mandobass. And parallel with banjos. That's where this bass banjo originated. Nowadays it's a (terrifying) novelty, but in its day, it was part of a multi-piece banjo orchestra (a truly blood-curdling prostpect).
The legendary Gibson designer Lloyd Loar was at Gibson in those days, and these were the times that drove his great acoustic designs.
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