Mikhail Glinka (1804-1857) was the first Russian composer to embrace Russian nationalism in his music, and the first notable Russian opera composer.  He found international fame with his opera Russlan and Ludmilla, first performed in St Petersburg in 1842. His Russian style was taken up by several Russian composers after him, including BorodinMussorgsky,  to a lesser extent - Tchaikovsky, and then also Rimsky-Korsakov.