The term ruan refers to one of China’s ancient but extinct plucked-string instruments. It is also known as ruanxian, and is a four-stringed, round-bodied plucked lute. Its history can be traced to the Han Dynasty (202 BC to 220 AD).
During the evolution of the Chinese orchestra in the 1970s, the ruan, a once obsolete instrument, was recreated as the lower-pitched instrument among the plucked-string family. Variations of the ruan, like the gaoyin ruan (soprano ruan), xiaoruan (small ruan), zhongruan (alto ruan), daruan (bass ruan) and diruan (also known as bass ruan), were also created based on the need of sound balance in orchestra.
Amongst the above, most Chinese orchestras use the zhongruan and daruan as a standard.