The gayageum or kayagum is a traditional Korean zither-like string instrument, with 12 strings, though some more recent variants have 21 or other number of strings. It is probably the best known traditional Korean musical instrument. It is related to other Asian instruments, including the Chinese guzheng, the Japanese koto, the Mongolian yatga, and the Vietnamese đàn tranh.
The sanjo gayageum is believed to have evolved in the 19th century with the emergence of sanjo music—which literally means scattered melodies, a musical form that involves fast tempos and some improvisation. The sanjo gayageum version of the instrument has closer string spacing and a shorter length to let musicians play the faster passages required for sanjo (Choi 2005). The sanjo gayageum is now the most widespread form of gayageum. (KCMPC 2001). All traditional gayageum use cotton strings, though, since the late 20th century, some musicians use nylon.
There are 6 or more schools of the gayageum sanjo, currently:
Seong Geum Yeon, Kim Juk Pa, Kin Yoon Deok, Kang Tae Hong, Kim Byeong Ho, Choi Ok Sam school.