c. 1908–1923Reputable sourceWell documented
Schoenberg and the End of Tonality
On the timeline · around c. 1908–1923 · The Recording Age
What happened
The Austrian composer Arnold Schoenberg led music beyond the tonal system that had organized it for centuries. First writing 'atonal' music with no home key, he then devised a rigorous 'twelve-tone' method that treats all twelve notes of the chromatic scale as equals, arranging them in ordered rows.
Why it matters
Schoenberg's break with tonality was one of the most radical events in the history of Western music. His twelve-tone technique shaped much of twentieth-century art music and remains a defining fork in the road for composers.