s. And the 20th Century has come up with a new tonal music that swept the world, with roots in Impressionism, folk and African music, and even a little Classical - namely, Jazz, Swing, Blues, and eventually, Rock.
In the realm of symphonic music, the beginning of the 20th Century was a watershed time, when major composers were taking chromaticism (the slippery slope between keys) to extremes, mixing tone-colors so thickly it was blurring the lines of harmony, with the consequence of new works becoming bigger, but not really all that different - and every composers likes to feel "unique", for whatever reason.