The earliest use of the word ''guan'' can be trace back to Zhou Dynasty records, where it refers to end-blown bamboo flutes such as the ''xiao'' or ''paixiao''. The earliest double-reed instrument appears in the late Zhou dynasty and is referred as ''hujia'' because it had been introduced from the of China. During that time, the ''hujia'' was used as the primarily military instrument for signaling, and is depicted in early Chinese poetry as raucous and barbaric.
The ''guan'' was developed after the ''hujia'' in the Tang Dynasty due to the flourishing music and art culture that were influenced by the silk road trade. Like the ''hujia'', it was probably adopted from Central Asian nomads, and became an important leading instrument in the court and ritual music. At the height of the Tang Dynasty, the ''guan'', alongside many other instruments was introduced to neighboring countries, where the ''guan'''s descendants are still used today.
However, in subsequent dynasties, the ''guan'' fell out of use in court music but became very popular in folk ensembles. It plays an important part in the wind-and-percussion ensembles that play on traditional festivals and celebratory occasions and is still popular in the wind band music of northern China, as well as in some other Chinese regions. In the Beijing opera orchestra, the ''guan'' is used to depict military scenes along with the ''suona'' and other percussion instruments.
The ''guan'' consist of a short cylindrical tube made of hardwood in northern China, where the instrument is called ''bili''. In the Guangdong region of southern China, it is made from bamboo and is called ''houguan'' . Traditionally the instrument has seven finger holes on the top and one thumb hole on the back. The length of the guan varies from 7 inches to 13 inches .
The northern ''guanzi'' comes in various keys and the ''houguan'' is available in three sizes.
In the 20th century, modern versions of the ''guan'' were developed in China. These modernized ''guan'' have extra holes and are fitted with metal keys to provide a wider and fully chromatic range. Such instruments are used primarily in large traditional orchestras.
All ''guan'' have a large, wide double reed made from ''Arundo'' cane, which is inserted into the top end of the tube.
The instrument's range is about two and one-half octaves. It has been used in a variety of musical contexts over the centuries, often as a solo instrument used to evoke a mood of sadness.
''Guan'' is capable of doing vibrato and wide pitch bends.
The ''guan'' is quite difficult to play, largely due to the difficulty of controlling the embouchure; a Chinese saying states that "the '''' takes 100 days to learn, but the ''guan'' takes 1,000 days to learn."
* from The Musical Instruments E-book