The traditional tale of Glinka as the father of Russian music is true in one sense, in that he was the first Russian composer to succeed on the international scale, but there's a big question: what do you mean by "Russian"? Glinka was trained in Italy and Germany, and his music has all of the accompanying stylistic features. So if you're looking for something distinctly Russian, and by that you mean music with Russian folk influences, compound meters, etc., then Glinka isn't your guy.