I don’t disagree with Sabby Sagall’s account of Russian music and modernism (December SR) but I do want to add a few extensions. The article mentions that Stravinsky did not like the revolution and left Russia, but it was more than dislike. As he wrote to the Nazis to get himself listed as an Aryan composer:
“I loathe all communism, Marxism, the execrable Soviet monster, and also all liberalism, democratism, atheism, etc.” And elsewhere: “I don’t believe that anyone venerates Mussolini more than I… I know many exalted personages, and my artist’s mind does not shrink from political and social issues. Well, after having seen so many events and so many more or less representative men, I have an overpowering urge to render homage to your Duce. He is the saviour of Italy and — let us hope — Europe.”
Prokofiev was also not a fan of the Bolsheviks but liked Stalin. Recent research has revealed that he was a Christian Scientist, and his problems with the authorities were in part due to his over eagerness to please his masters. When he wrote happy music to show how nice Russia was, the authorities thought he was being ironic and taking the piss when he was just trying to comply.
A general point to add is that from the late 19th century classical music borrowed and learnt (some say filched) from folk music. This is particularly true of Stravinsky learning from Russian folk music, but it was a general trend in modernism. Just as Picasso learnt from African art so classical music learnt from folk, blues, jazz and later dance music.
It was also an aim of the Russian Revolution to break down the barriers between high and low art — Shostakovich played piano to silent films and wrote film music. This aspect of modernism was taken up in the 1930s by Bertolt Brecht and continues today.