The origins of the Black Bottom are lost in the traditions of early African Americans. My source for this is Wikipedia.
The black bottom is a dance which became popular in the 1920s, danced solo or by couples. It took over in popularity from the Charleston.
Originating among African Americans in the rural South, the black bottom eventually was adopted by mainstream American culture and became a national craze in the 1920s. The dance was most famously performed by Ann Pennington, a star of the Ziegfeld Follies, who performed it in a Broadway revue staged by Ziegfeld’s rival George White in 1926.