The guzheng, or gu zheng or zheng  (gu - 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/kayagum, and the Vietnamese dàn tranh.

The modern-day guzheng is a plucked, half-tube zither with movable bridges and 21 strings, although it can have anywhere from 15 to 26 strings (or even more than 44 strings). The guzheng's strings were formerly made of twisted silk, though by the 20th century most players used metal strings (generally steel for the high strings and copper-wound steel for the bass strings). Since the mid-20th century most performers use steel strings flatwound with nylon. Each string is suspended over the upper soundboard by a single adjustable bridge which can be moved to tune the instrument, so the guzheng can in principle be tuned to any scale.

The guzheng has a large resonant cavity made from wu tong wood (Firmiana platanifolia). 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, having 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. 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" or "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. Two broad playing styles (schools) can be identified as Northern and Southern. The Northern styles are associated with Henan and Shandong while the Southern style is with the Chaozhou and Hakka regions of eastern Guangdong. Both Gao Shan Liu Shui (High mountains flowing water) and Han Gong Qiu Yue (Han palace autumn moon) are from the Shandong school, while Han ya xi shui (Winter Crows Playing in the Water) and Chu shui lian (Lotus Blossoms Emerging from the Water) are major pieces of the Chaozhou and Hakka repertories respectively.

Photo: guzhengman (Flickr.com)

Many new pieces have been composed since the 1950s which used new playing techniques such as the playing of harmony and counterpoint by the left hand. Contemporary experimental atonal pieces have been composed since the 1980s.

During its early development, the zheng was strongly associated with the people and the state of Qin in Western China – now Shaanxi province and its surrounding areas. During the 2nd century BC, the zheng was popular in the music of southern Shanxi and Gansu provinces. At the time it was described as having 12 red silk strings, with narrow spaces between them, and high narrow jade bridges. The zheng in the Tang dynasty (AD 618-907) had 13 strings, and in succeeding dynasties the number of strings increased to 14 and 15. The Japanese koto is an imported version of the 13 string zheng.

In ancient times, the zheng was an important ensemble instrument, in contrast to its modern use as a solo instrument, and was an integral part of folk music ensembles in towns across China, as well as part of the court banquet music ensemble in the Ming and Qing dynasties (14th–early 20th centuries). As a result, the zheng is quite an unusual instrument in China , being associated with the "low" traditions of narrative song singing, as well as the "loftier" traditions of court ensemble music.

The earliest records of the guzheng, which was also known as the Qin Zheng, are from the ShaanBei region of North West China. There are records from the Qin dynasty of the prime minister Li Si referring to the Qin Zheng. However archaeologists have also discovered the instrument in Jiangsu province in the east. There's a legend about the origins of the guzheng. An ancient instrument the se – a zither like the guzheng was split into two. One half became the guzheng and the other half became the guqin.

Modern traditions for the guzheng are a combination of regional styles, transmitted from master to pupil, and "national" repertoire developed during the 20th century. The best known regional styles for the zheng are the northern styles of Henan and Shandong , the southern style of Chaozhou, and the western Shaanxi style, which developed during the Ming and Qing dynasties. Each of these different areas developed their own repertoire, drawing on local folk music as well as the music of other instruments such as guqin and pipa. The different regional styles all have their characteristic tuning, with some notes slightly flat, and some notes with more standard tuning.

After 1949 when guzheng started to be taught in music academies, the regional styles became less and less evident and are now disappearing. When you listen to traditional folk music you can still hear the difference, but when listening to modern compositions you can barely tell the difference.

While a great deal of guzheng repertoire is based on local folk music, many pieces were adapted from the repertoire of the guqin. Different instruments sharing music is one of the characteristics of Chinese music. A characteristic of music in China are several mother pieces, for instance BaBan. Most of zheng music was adapted from Baban. These mother pieces are the basic raw material for Chinese music.

The zither is a stringed musical instrument, derived from the psaltery and the dulcimer. It has a flat sound box over which are stretched from 12 to 45 strings; these are plucked with the fingers and a plectrum. The term zither is also used generically for various instruments, including the dulcimer, the psaltery, and several Asian instruments. The psaltery originated in the Middle East and is referred to in the Bible. It appeared in Europe in in the 12th century and flourished until the late Middle Ages. The name 'zither' refers both to a specific instrument and the name of a family of chordophones. The characteristic feature of this family is the zither's structure - essentially, it is a wooden sound box; unlike the guitar or violin, it has no 'neck'. Wire (or sometimes gut) strings run the length of the sound box. They date back at least to 2000 B.C., when variants such as the psaltery were used by ancient Greek and Egyptian cultures. Portable, accessible, easily constructed and easily played, these instruments may be plucked (that is - you use a 'pick' to strum the strings) or struck with wooden mallets.

Some content borrowed from a China Roots radio broadcast (w/ Prof. Zhang Zhentao from the Music Research Institute in Beijing and Wang Jing).