The black bottom is a dance which became popular in the 1920s—the Roaring Twenties, also known as the Jazz Age, and the era of the flapper. It was danced solo or by couples.

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.

—–wikipedia