The Ballets Russes were a company of ballet dancers whose full title was Les Ballets Russes de Serge Diaghilev. They became extremely famous in Europe in the early part of the 20th century.
The group was formed and directed by the Russian Sergei Diaghilev. The Ballets Russes had more influence on ballet and ballet music than any other ballet company of their time. The dancers were from Russia, but the group travelled throughout Europe, spending a lot of their time based in Paris. Stravinsky was one of the many composers who wrote ballet music for them.
Sergei Diaghilev was an impresario who was extremely good at spotting good dancers and helping them to rise to great standards. He had very good taste in art and music and inspired some great composers to write music for his dancers. He got some of the most famous painters of his time to make set designs for his productions.