The erhu, a two-stringed bowed musical instrument, is made of wood for its resonator, which is covered at one end with a snake skin. It is strung with two metal strings, with the inner and outer strings separated by a pure fifth. The standard tuning is usually with the inner string set to d1 and the outer string set to a1. The playing techniques of the erhu are very rich, including left-hand techniques such as bowing, natural harmonics, artificial harmonics, tremolo, thumb-sliding glissando, and string plucking, and right-hand techniques such as staccato bowing, spiccato, tremolo, and pizzicato. Playing the erhu requires a coordinated effort from both hands.
The erhu, also known as the "Huqin," appeared in the Tang Dynasty and was called "Xiqin," a folk instrument from the north. It is generally believed that the modern Huqin evolved from the Xiqin and has now become a unique and captivating string instrument in China. It is suitable for expressing deep and sad emotions, as well as describing grand and impressive landscapes.