Program music became popular due to its close relation to literature. Liszt's Les Preludes, Strauss's Don Juan and the Sorcerer's Apprentice by Dukas are all popular program music pieces. They are all in symphnic poem form. It uses tradtional froms such as rondo and sonato forms. Nationalism is where a composer uses a national identity in their music.
Music come from the native land in forms of folk songs, legends, and dances.
Sibelius used insopiration from his native country to write one of his best works, Finlandia. Puccini was an Italian composer. He had a great sense of theater which made his works hard to forget. He used many small forms such as librettos. He also followed the verisimo trend or realism.