Composed in 1982, Tres Cantos Nativos dos Indios Krao is freely based on melodies sung by the Krao tribe - a group of native Brazilian indians who live in the Xingu river area of the Amazon forest of northwestern Brazil.  The use of percussion instruments is strongly recommended by the composer; the instruments should emphasize and improvise on the rhythms of the chorus.  The meaning of the text is unknown; it was treated by the composer as a group of phonemes.