There exists evidence of the use of music as a means to accompany dance in ancient times and throughout all recorded history. In Western academic music tradition, the composition of dance pieces and the establishment of dance forms is usually the outcome of the mutual influence that academic and popular music have on each other. The result is that sometimes a dance form will acquire a level of complexity and musical detail that may render some expressions of it as unable to actually accompany the activity of dance. In other words: Western classical music often takes popular dance forms and, using their formal structure and musical language as a basis, creates pieces meant for a sitting audience. Many of these musical expressions are of a nationalistic nature.