What is "koanga"

Koanga is an opera with music by Frederick Delius, his third opera, written between 1896 and 1897, and a libretto by Charles F. Keary, inspired partly by The Grandissimes: A Story of Creole Life of George Washington Cable. Inspiration also came from Delius's own experiences as a young man when his family sent him to work in Florida. Delius himself thought well of the opera compared to its predecessors, Irmelin and The Magic Fountain, because of the incorporation of dance scenes and his treatment of the choruses. Koanga is reputed to be the first opera in the European tradition to base much of its melodic material on African-American music.