Cai Lun presents papermaking to the Han court

Chinese books were written on strips of bamboo or wood, which were heavy and awkward, or on silk, which was too costly for everyday use. Cai Lun, a native of Guiyang Commandery (modern Leiyang in Hunan), had served in the palace at Luoyang since about 75 and from 88 or 89 headed the Shangfang, the workshops that made weapons and instruments for the court. According to his biography in the Book of the Later Han, he had the idea of making paper from tree bark, hemp ends, rags and fishing nets and submitted the method to the throne in the first year of the Yuanxing era (105). The emperor praised it, the new paper came into use everywhere, and it became known as “the paper of Marquis Cai” — in 114 Cai Lun was made Marquis of Longting.

Cai Lun did not invent paper from nothing: archaeological finds show that paper was made in China long before him, and the earliest known fragment, from Fangmatan in Gansu, dates from 179–141 BC and was probably part of a map. His achievement was to improve and fix the process, adding tree bark (probably mulberry) and waste fibres, so that paper could be made on a large scale. The main source on him is some 300 characters in the Book of the Later Han, compiled in the 5th century from earlier records.

Paper came into general use in China, spread to Vietnam, Korea and Japan in the following centuries, reached Samarkand by 751 and the Islamic world in the 8th century, and appeared in Europe in the 11th–12th centuries. Cai Lun himself fell after the death of his patron, Empress Dowager Deng, in 121: summoned by Emperor An to answer for his part in the death of the emperor’s grandmother, Consort Song, decades earlier, he took poison. He was later revered in China as the god of papermaking.