However, modernism in music became increasingly prominent and important; among the most important modernist precursors were Alexander Skryabin, Claude Debussy, and the post-Wagnerian composers such as Gustav Mahler and Richard Strauss, who experimented with form, tonality and orchestration. Busoni, Stravinsky, Schoenberg, and Schreker were already recognized before 1914 as modernists, and Ives was retrospectively also included in this category for his challenges to the uses of tonality.