Simplify the following text for a Grade 6 native English-speaking person.
Original: Ravel began work with impresario Sergei Diaghilev during 1909 for the ballet Daphnis et ChloÃ commissioned by Diaghilev with the lead danced by the famous ballet dancer and choreographer , Vaslav Nijinsky .
Simplified: They were the worldâ s most famous ballet group . Their director Diaghilev asked Ravel to write a ballet for them Ravel took about three years to compose the music for Daphnis et ChloÃ .