The zheng was popular as early as in the Warring States (475-221 BC), especially in the state of Qin in west China. That betrays the origin of the name qin zheng, Another hypothesis for its name came from a folk tale that se ( a large table harp) was split in half to settle a family quarrel between two sons, thus creating the first two zheng, In the Chinese character the lower portion for zheng happens to mean "quarrel".
The zheng's soundbox is constructed of wood, red sandal for its sides and bottom and wutong wood (firmiana platanifolia) for the arched soundboard, According to the historical texts, it was described as having 12 strings before the Han and Jin period (206-BC-AD 420). In succeeding periods the number of strings kept increasing; 13 after the Tang and Song (618-1279), 15 or 16 since the Ming and Qing (1368-1911), 21 since the 1960's, and 24 or 26 at present, Each string is suspended over the upper sound board by a single adjustable bridge as a device for fine tuning, The strings are tuned to give three complete octaves of a pentatonic scale, sometimes of a heptatonic one.

The instrument is rich in playing techniques. The performer plucks the strings with his right-hand fingernails (either real or simulated), while his left-hand fingers apply pressure to the strings to execute vibratos, glissando, other embellishments and occasional plucking techniques,. Sounding melodious and elegant, it is as important solo instrument now, and often in accompaniments as well.
The guzheng, Chinese forerunner of the Japanese koto and Korean kayagum, originated over 2300 years ago and is one of the oldest plucked instruments in China. Because of its melodic qualities, the Guzheng was extremely popular for both court and folk music. The sound box is made of paulownia wood; the strings, varying in number from thirteen to twenty-five, used to be made of silk, but are nowadays metal or nylon. They are tuned to a pentatonic scale with a range of more than four octaves.

Andrea: I agree that guzheng's sound is more melodious than guqin, yet I think it's v. impractical (not that I wanna bring guqin to a picnic ). One more question, why does guzheng is relqtively cheaper than guqing?