Erhu, also called Huqin, was known as Xiqin during the Song Dynasty. Huqin described in Yuan Dynasty records was the real forerunner of the modern Erhu, having its stem, sound box and pegs made of wood. The sound box can be round, hexagonal or octagonal, with one end covered with snakeskin, sometimes from a python, and the other end, an ornamentally carved sound vent. There are two strings, played with a bamboo bow with horsetail hairs passing behind the strings. The range is normally five octaves, and sometimes four in special cases. In modern times, many people have made innovations to improve the tone color of Erhu.
The most widespread piece of Erhu music in China is Two Springs Reflect the Moon, composed by the Wuxi folk artist Ah Bing, whose original name was Hua Yanjun, in the mid 20th century. This work has two themes, which complement and intertwine, and finally melt into each other subtly and smoothly. Step by step and variation upon variation, the two themes rise and fall effortlessly. The crescendos especially show the composer's steely and unyielding spirit.
There is a profound range of feeling in this piece, which incorporates a majestic spirit within a tightly knit composition. Vigorous variations in bowing technique make full use of the five hand positions, and the result is a fiercely emotional coloring expressing of the composer's suppressed grief at having tasted to the full the bitterness of life in the old society. Two Springs Reflect the Moon is an exquisite example of Chinese instrumental folk music stemming from the heart of a small-town folk artist.