Bamboo and wooden slips

Bamboo and wooden strips (simplified Chinese: 简牍; traditional Chinese: 簡牘; pinyin: jiǎndú) are long, narrow strips of wood or bamboo, each typically holding a single column of several dozen brush-written characters. They were the main media for writing documents in China before the widespread introduction of paper during the first two centuries AD. (Silk was occasionally used, for example in the Chu Silk Manuscript, but was prohibitively expensive for most documents.)
Strips of wood or bamboo vary primarily in length. For bamboo manuscripts, the strips can go from as short as 9 cm to as long as 45 cm. The width is more consistently around 0.6 cm. The writing proceeds vertically, from right to left. Strips were bound together with hemp, silk, or leather and used to make a kind of folding book, called jiǎncè or jiǎndú. The binding process usually takes place after the writing, with a few exceptions.
The earliest surviving examples of wood and bamboo slips date from the 5th century BC during the Warring States period. However, references in earlier texts surviving on other media make it clear that some precursor of these Warring States period bamboo slips was in use as early as the late Shang period (from about 1250 BC). Bamboo and wooden strips were the standard writing material during the Han dynasty and excavated examples have been found in abundance. Subsequently, the improvements made to paper by Cai Lun during the Han dynasty began to displace bamboo and wooden strips from mainstream uses, and by the 4th century AD bamboo had been largely abandoned as a medium for writing in China.
The custom of interring books made of the durable bamboo strips in royal tombs has preserved many works in their original form through the centuries. An important early find was the Jizhong discovery in 279 AD in a tomb of a king of Wei, though the original recovered strips have since disappeared. Several caches of great importance have been found in recent years.
In 1930, the Sino-Swedish Expedition excavated ten sites in the Juyan Lake Basin and unearthed a total of 10,200 wooden slips dating to the Western Han, a cache that came to be known as the "old Juyan texts". In 1937, after the Second Sino-Japanese War began, Chung-Chang Shen transported these wooden slips from Beijing to the University of Hong Kong. Another 20,237 slips were excavated between 1972 and 1976 by the Juyan Archaeological Team, Gansu. These slips are held by the Provincial Museum of Gansu and came to be known as the "new Juyan texts".
The Shanghai Museum corpus was purchased in Hong Kong the year after the Guodian tomb was excavated, and is believed to have been taken by graverobbers from a tomb in the same area. The Tsinghua collection was donated by an alumnus who purchased it through auction, with no indication of its origin. The Anhui University corpus was also purchased by Anhui University after the strips surfaced in the antiquity market. The others were archaeologically excavated.
One accoutrement used when writing on bamboo slips was a small knife which would be used to scrape away mistakes and make amendments. Decorated knives became a symbol of office for some officials indicating their power to amend and change records and edicts.