The oldest known scheme of classifying instruments is Chinese and dates from the 3rd millennium BC. It grouped instruments according to the materials they are made of. Instruments made of stone were in one group, those of wood in another, those of silk are in a third, and those of bamboo in a fourth, as recorded in the Yo Chi (record of ritual music and dance), compiled from sources of the Chou period (9th-5th centuries BC) and corresponding to the four seasons and four winds.
The eight-fold system of pa yin (八音 "eight sounds", "octave"), from the same source, occurred gradually, and in the legendary
Emperor Zhun's time (3rd millennium BC) it is believed to have been presented in the following order: metal (chin), stone (shih), silk (ssu), bamboo (che), gourd (piao), clay (t'u), leather (hoes), and wood (mutt) classes, and it correlated to the eight seasons and eight winds of Chinese culture, autumn and west, autumn-winter and NW, summer and south, spring and east, winter-spring and NE, summer-autumn and SW, winter and north, and spring-summer and SE, respectively.
However, the Chou-Li (Rites of Chou), an anonymous treatise compiled from earlier sources in about the 2nd century BC, had the following order: metal, stone, clay, leather, silk, wood, gourd, and bamboo. The same order was presented in the Tso Chuan (Commentary of Tso), attributed to Tso Chiu-Ming, probably compiled in the 4th century BC.
Much later, Ming dynasty (14th-17th century) scholar Chu Tsai Yu recognized three groups: those instruments using muscle power or used for musical accompaniment, those that are blown, and those that are rhythmic, a scheme which was probably the first scholarly attempt, while the earlier ones were traditional, folk taxonomies.
More usually, instruments are classified according to how the sound is initially produced (regardless of post-processing, i.e., an electric guitar is still a string-instrument regardless of what analog or digital/computational post-processing effects pedals may be used with it).