What is a compositional method that evolved beyond the major-minor tonal system and is not centered around a central key or scale?

One notable compositional method that evolved beyond the major-minor tonal system is atonality, prominently developed by composers like Arnold Schoenberg. Atonality rejects the hierarchy of pitches associated with traditional tonal music, instead utilizing all twelve tones of the chromatic scale without a central key or tonal center. This approach allows for greater freedom in melodic and harmonic structure, leading to innovative forms of expression in 20th-century music. Another related concept is the use of the twelve-tone technique, which organizes the twelve pitches into a specific sequence or "row," emphasizing equality among the notes.