Precolonial artistic expression emphasized ceremonial music, dance, sculpture, and oral literature. Christianity and colonialism had a great impact on these art forms. The carving of ritual objects became commercialized, and music and dance altered as a result of the introduction of Western instruments and musical styles. In the 1980s the Brazzaville region, along with Kinshasa, across the river in the Democratic Republic of the Congo, became a vital centre of contemporary African music. There are two libraries in Brazzaville, and a national museum contains collections of past history objects as well as precolonial and contemporary art.