Africa and Asia is also taught in Western universities. This includes the documented classical traditions of Asian countries outside the influence of Western Europe, as well as the folk or indigenous music of various other cultures. Popular or folk styles of music in non-Western countries varied widely from culture to culture, and from period to period. Different cultures emphasised different instruments, techniques, singing styles and uses for music. Music has been used for entertainment, ceremonies, rituals, religious purposes and for practical and artistic communication. Non-Western music has also been used for propaganda purposes, as was the case with Chinese opera during the Cultural Revolution.