Music of China appears to date back to the dawn of Chinese civilization, and documents and artifacts provide evidence of a well-developed musical culture as early as Zhou Dynasty (1122 BC - 256 BC). According to Mencius, a ruler had asked Mencius whether it was moral if he preferred pop songs to the classics. The answer was that the only thing matters being whether or not he loved his subjects. Imperial Music Bureau, first established in Qin Dynasty (221-207 BC), was greatly expanded under Emperor Han Wu Di (140-87 BC) and charged with supervising court music and military music and determining what folk music would be officially recognized. In subsequent dynasties, development of Chinese music was strongly influenced by foreign music, especially that of Central Asia.