The 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.
In North Korean 1970’s, Korean traditional instruments were advance contemporary styles, the number of the 12strings expanded to 21 strings and seating method also changed to western style using chair instead of seating on the floor in traditional when performers play the instruments. On the video, the woman is playing ‘Song of the Sea’ which is Korea traditional folk song arranged for 21 string new kayageum in North Korea.