As far as we know, some countries in the world also have one-stringed musical instruments such as Ektara and Gopi Yantra in India, Bangladesh, and Pakistan; Ichigenkin in Japan, Kse Diev in Cambodia and Pin Nahm Tao in Thailand, etc. Of them, two musical instruments from Cambodia and Thailand use the technique of overtones to produce sound. However, due to the limitations in performing style and sound volume, these instruments create timbre rather than being dynamic and flexible performing instruments like the Vietnamese Dan Bau.