What were the alternatives to tonality or centered music during the contemporary period?

During the contemporary period, alternatives to tonality included atonality, which disregards traditional tonal centers, and modal music, which explores scales outside the major/minor system. Additionally, composers embraced serialism, employing mathematical systems to organize pitch and rhythm. Other movements like minimalism and experimental music further expanded the boundaries of sound, incorporating unconventional structures and techniques. These approaches challenged established norms and opened new avenues for musical expression.