The guzheng, or gu zheng (Chinese: 古箏; pinyin: gǔzhēng) or zheng (箏) (gu-, 古 means "ancient") is a traditional Chinese musical instrument. It belongs to the zither family of string instruments.
The guzheng is the parent instrument of the Japanese koto, the Mongolian yatga, the Korean gayageum, and the Vietnamese đàn tranh.
The guzheng should not to be confused with the guqin, another ancient Chinese zither but without bridges.

Description
The ancestry of the guzheng can be traced back to two other Chinese plucked zithers, the se and the guqin. The guzheng has existed since the Warring States Period and became especially popular during the Qin dynasty. The number of strings on the guzheng has always fluctuated, as we have as few as 6 to as many as 23 strings during the Tang dynasty. The earliest record of the guzheng in Shi Ji is attributed to the historian Sima Qian in 91 BCE.
Until 1961, the common guzheng had 16 strings, although by the mid-20th century 18-string guzhengs were also in use. In 1961 Xu Zhengao together with Wang Xunzhi introduced the first 21-string guzheng after two years of research and development. In 1961, they also invented the "S-shaped" left string rest, which was quickly adopted by all guzheng makers and is still used today, whether in the shape of the letter "S", "C", etc. This curve allows for greater ease in tuning the strings and, combined with strings of varied thickness, allows for greater resonance in both the deeper and higher pitch ranges; thin timbre was a result of simply adding more strings to the instrument, a problem encountered in the making of the "improved" gayageums of North Korea. The 21-string zheng is the most commonly used, but some traditional musicians still use the 16-string, especially along the southeastern coastal provinces of China and in Taiwan.
The guzheng is tuned to a pentatonic scale, the 16-string zheng is tuned to give three complete octaves, while the 21-string zheng has four complete octaves.

Playing styles and performers
The guzheng has been used by the Chinese performer Wang Yong (王勇) in the rock band of Cui Jian, as well as in free improvised music. Zhang Yan used it in a jazz context, performing and recording with Asian American jazz bandleader Jon Jang. Other zheng players who perform in non-traditional styles include Randy Raine-Reusch, Mei Han, Zi Lan Liao, Levi Chen, Andreas Vollenweider, Jaron Lanier, Mike Hovancsek, and David Sait. The American composer Lou Harrison (1917–2003) played and composed for the instrument. Jerusalem based multi-instrumentalist Bradley Fish is the most widely recorded artist of loops for the guzheng. Fish is known for using the guzheng with a rock-influenced style and electronic effects on his 1996 collaboration "The Aquarium Conspiracy" with Sugarcubes/Björk drummer Sigtryggur Baldursson. The virtual band Gorillaz used the guzheng in their song "Hong Kong" from the Help: A Day In The Life compilation. The Canadian composer Kevin Austin[1] has written several pieces for guzheng and electroacoustic sounds, among them Three traditional Pieces (2003), Four Arts (2006), and the larger Ritual Mosaic of Masks, Mirrors and Shadows in 2006 commissioned by a Chinese-Canadian virtuoso guzheng performer Chih-Lin Chou[2]with assistance of Canada Council of Arts, for guzheng, violin, percussion, video Freida Abtan,and six-channels of ea.

Listening

Guzheng video from Robert Garfias site
Video of Jiang Xiao-Qing with Ryuichi Sakamoto
Cover of "All Along the Watchtower" by Bradley Fish, with steel-string acoustic guitar and guzheng