Simplify the following text for a Grade 10 native English-speaking person.
Original: Sergei Pavlovich Diaghilev ( \/ Sergei Pavlovich Dyagilev ) ( -19 August 1929 ) , usually referred to outside of Russia as Serge , was a Russian art critic , patron , ballet impresario and founder of the Ballets Russes , from which many famous dancers and choreographers would later arise .
Simplified: Sergei Pavlovich Diaghilev ( also known as Serge ) , ( Russia , 31 March 1872 â `` 19 August 1929 ) was a Russian art critic , patron and ballet impresario . He formed a ballet company called Les Ballets Russes de Serge Diaghilev .