Mikhail Glynka was the first Russian composer to gain widespread fame in his own country. The aristocracy still took their lead from French (and German) influences, and so composers from those lands were favored. Glynka was a groundbreaker, writing classical music that combined both French and Russian influences, most notably Russian themes. His opera Ruslan and Ludmilla was based on a poem by Alexandr Pushkin - you don't get much more Russian than that.
The great Russian composers known as "The Five" (most famous of which was Modest Mussorgsky) owed their opportunity to the foundation laid by Glynka.
This is without doubt his most famous piece, and some of you will recognize it.