A musical source whose potential was also used for experimentation is folklore. While previous generations of composers had repeatedly chosen exotic subjects in order to legitimise structures that deviated from the prevailing rules of composition, it was in the work of Claude Debussy that a stylistic and structural adaptation of javanese gamelan music, which he had become acquainted with in 1889 at the Paris 1889 World's Fair, can be observed for the first time. In this context, the work of Béla Bartók, who had already explored most of the fundamental characteristics of his new style by means of a systematic study of Balkan folklore in 1908, is to be regarded as exemplary. In the course of this development, Bartók arrived at the treatment of the "piano as a percussion instrument" with his "Allegro barbaro" (1911), which subsequently had a decisive influence on composers' treatment of this instrument. The rhythmic complexities peculiar to Slavic folklore were also appropriated by Igor Stravinsky in his early ballet compositions written for Sergei Diaghilev's "Ballets Russes". Significantly, Stravinsky uses a given "barbaric-pagan" stage plot for his most revolutionary experiment in this respect ("The Rite of Spring" 1913).