The Music Bureau (Traditional Chinese: 樂府; Simplified Chinese: 乐府; Hanyu Pinyin: yuèfǔ, and sometimes known as the "Imperial Music Bureau") served in the capacity of an organ of various imperial government bureaucracies of China: discontinuously and in various incarnations, the Music Bureau was charged directly, by the emperor (or other monarchical ruler), or indirectly, through the royal (or imperial) government to perform various tasks related to music, poetry, entertainment, or religious worship. These tasks included both musical and lyrical research and development, and also directing performance acts. The existence of a Music Bureau was typical of various Chinese dynasties, though the Music Bureau's prominence and influence may have peaked during the reign of Han Dynasty emperor Wu, who was especially interested in such activities and engaged himself accordingly. The songs/poems collected or developed by the Han music bureau received the appellation of "yuefu"; but, eventually, the term "Music Bureau", or yuefu (also, yueh-fu) also came to be applied to a category of Classical Chinese poetry which was based upon the standard forms and themes documented or promoted by the Music Bureau staff during the Han Dynasty. Known as yuefu (meaning, "in the style of the Music Bureau poetry), this type of poetry made major contributions to Han poetry, as well as the Jian'an poetry of the late Han and early Six Dynasties. There was also an important and later Tang poetry literary revival of the yuefu poetic forms. The mission of the Music Bureau was concerned with poetry, music, and their live performances, because these concepts were not really considered to be distinct: lyrics are a part of music, and traditional Chinese poems, particularly shi were considered to be suitable for chanting or singing, and poetic verses in accompaniment with instrumental music were often presented together as integral parts of performances. In the case of the Music Bureau, performances were oriented towards religious rites or entertainment in service to the emperor.
More Detail: http://en.wikipedia.org/wiki/Music_Bureau