Just recently, I found out my friend Yoon plays a Korean musical instrument called a Kayagum. Yoon has told me she knows many of the traditional folklore songs, and has been playing about ten years. She has also taught others to play the kayagum. The kayagum is one of the most representative national instruments of Korea.
Historically, the instrument can be traced back to the Kaya kingdom (42-562 AD) in Korea and appears to be modeled on the Chinese Zheng. The Japanese Koto is similar to the Kayagum with three major differences: The kayagum is played by plucking the strings with the bare fingers, the koto is played with three picks attached to the thumb, fore and middle fingers; The kayagum is played with the head of the instrument in the player’s lap and the tail of the instrument on the floor, while the koto is played with the instrument lying on the floor; The kayagum’s strings vary with pitch— larger diameter strings for lower-pitched strings and smaller diameter for higher-pitched strings, while the koto’s strings are uniform in diameter. Both instruments are made of paulowina wood, but the underside of the kayagum is often made of chestnut.
The traditional kayagum has 12 strings, although modern variants have 19, 21, or 25 strings. Among traditional kayagum, there are two major design variants— court and sanjo. The primary difference is the court kayagum— also called a silla-gum— is larger and has "horns" or "prongs" at the tail of the instrument. The silla-gum derives it’s name from the Silla dynasty of Korea, and was developed after the Silla kingdom conquered the Kaya kingdom during the sixth century AD. The sanjo variant was developed about 150 years ago, when sanjo music first became popular. The sanjo variant has tighter spacing between the strings and is slightly shorter in length— both changes to accommodate the faster playing style required by most sanjo and pyongch'ang music. The kayagum can be played solo, as a part of a duet or a trio.
As I find out more about other traditional Korean musical instruments, I'll post the information here.