The Erhu (also known as Huqin) is a two-stringed, bowed instrument, dating back well over a thousand years and is said to have been introduced into China during the Song Dynasty. It evolved from its early ancestor, the Xi Qin, of the Xi minority nationality residing in the north of China. The Chinese residing in the Central Plains regarded the minorities as barbarians, or the Hu people, and hence, their instrument was dubbed the Huqin, literally "the barbarian's fiddle".

The Erhu has two floating strings (fixed at quinta, commonly tuned to D-A) with an irremovable bow clasped in between. It has an elegantly long and slender wooden neck, ending in a pair of tuning pegs that stand serially. A metal clamp or silk string clamp on the neck acts as a capo to change the open pitches of the strings. A small, wooden sound box, which usually rests on the musician's left thigh, is covered with stretched snakeskin, which gives it a distinctly mellow, yet bright, tone. The sound box may be hexagonal, octagonal or circular, depending on the make and model. The scroll of the Erhu may be ending in a simple crescent, ornamentally adorned with metal or carved into a dragon's head.

Although "barbaric" in origin, the tonal quality of the Erhu has become extremely versatile due to constant improvements throughout history. Its musical capabilities are wide-ranging, from soft and touching (even lamenting) to forceful and lush depending on the different regional styles of playing and the strength applied. Its mid-tones are gentle, while the high tones are clear. A wide range of three octaves, with an average reach of six inches between octaves, the Erhu is challenging to the student, requiring deft finger-work and a well-trained ear.

Under the influence of the regularly trained musician Liu Tianhua (1895-1932) and the local minstrel Hua Yanjun (known as the "blind man Ah Bing") (1893-1950) during the 1920's, the Erhu developed into a solo instrument. Today, the Erhu is one of the most popular instruments in modern China, and has spread its influence to most of East Asia, and even has regular appearances in Hollywood soundtracks.

On stage, the Erhu is widely used as the melody-carrying instrument in the orchestra, and has two compatriots from the Huqin family: the Gaohu and the Zhonghu (literally "the high fiddle" and "the medium fiddle", respectively), the former with a higher pitch and sounds brighter, the latter with a medium pitch and sounds more mellow. Both the Gaohu and the Zhonghu were more recently developed for orchestral purposes, but have also begun to claim their own stakes as solo instruments. The Erhu is also widely used in the accompaniment of song and dance.