It also does not include technologies developed elsewhere and later invented separately by the Chinese, such as the odometer, water wheel, and chain pump.
The following is a list of the Four Great Inventions—as designated by Joseph Needham (1900–1995), a British scientist, author and sinologist known for his research on the history of Chinese science and technology.
Although it is recorded that the Han Dynasty (202 BC – AD 220) court eunuch Cai Lun (50 AD – AD 121) invented the pulp papermaking process and established the use of new materials used in making paper, ancient padding and wrapping paper artifacts dating to the 2nd century BC have been found in China, the oldest example of pulp papermaking being a map from Fangmatan, Tianshui; by the 3rd century, paper as a writing medium was in widespread use, replacing traditional but more expensive writing mediums such as strips of bamboo rolled into threaded scrolls, strips of silk, wet clay tablets hardened later in a furnace, and wooden tablets.
The earliest known piece of paper with writing on it was discovered in the ruins of a Chinese watchtower at Tsakhortei, Alxa League, where Han Dynasty troops had deserted their position in AD 110 following a Xiongnu attack.
In the paper making process established by Cai in 105, a boiled mixture of mulberry tree bark, hemp, old linens and fish nets created a pulp that was pounded into paste and stirred with water; a wooden frame sieve with a mat of sewn reeds was then dunked into the mixture, which was then shaken and then dried into sheets of paper that were bleached under the exposure of sunlight; K. Tom says this process was gradually improved through leaching, polishing and glazing to produce a smooth, strong paper. Woodblock printing: The earliest specimen of woodblock printing is a single-sheet dharani sutra in Sanskrit that was printed on hemp paper between 650 and 670 AD; it was unearthed in 1974 from a Tang tomb near Xi'an.
14th to early 15th century) and Liu Bowen (1311–1375).