Angklung, is a traditional music instrument made out of two bamboo tubes attached to a bamboo frame. The tubes are carved so that they have a resonant pitch when struck. The two tubes are tuned to octaves. The base of the frame is held with one hand while the other hand shakes the instrument rapidly from side to side. This causes a rapidly repeating note to sound. Thus each of three or more Angklung performers in an ensemble will play just one note and together complete melodies are produced. This traditional music originally from Sunda, West Sumatra, Indonesia, but now very popular in South East of Asia. Even the Sundanese people used this music since ancient times.
In the time of Padjajaran Kingdom (Hindu period), the people used the Angklung for sign of prayer time. When the Padjajaran Kingdom had conflict with the greatest Kingdom in Indonesian ancient times, Majapahit, the angklung used for the corps music in the wartimes. When the time of Dutch imperialism, the Dutch government forbid this music, because this angklung can be the spirit and symbol for the anti imperialism.
The Angklung got more international attention when Daeng Soetigna, from Bandung, West Java, expanded the angklung notations not only to play traditional pelog or slendro scales, but also diatonic scale in 1938. Since then, angklung is often played together with other western music instruments in an orchestra. One of the first well-known performances of angklung in an orchestra was during the Bandung conference in 1955. A few years later, Udjo Ngalegena, a student of Daeng Soetigna, opened his "Saung Angklung" (House of Angklung) in 1966 as centre of its development.
There are many video of Angklung which you can see in youtube, but this is very interesting.
This is Angklung Performance by Keluarga Paduan Angklung (KPA) Institut Teknologi Bandung (ITB), Indonesia, with Song, "Mission Impossible". Taken from: ivankurniawanooze
Another site : saung angklung udjo