Impressionistic music and art started around the late 1800’s in the Romantic Era.  Composers and artists started to move away from the basic structure of major and minor sounds and solid lines and started using the whole tone scale and pentatonic scale amongst other world scales.  The music can sound dreamy and art also reflects this.  The music can be played by an orchestra or soloist.  Debussy was one of the main composers.

BBC Bitesize Impressionism