The relations between the notes of the scale and the rules governing them were understood very early in China. Musical tones of a fixed pitch were called Lu and these tones had been investigated as early as in the Spring and Autumn Period (770-476BC). The study of musical tones of course sprang from actual practice of the playing of music, but it was not long before it became separated from musical practice. In the Warring States Period (475-221BC) there was thought to be some internal harmony between music and the calendar, simply because there were 12 Lu and the year had 12 months.

In the Ming Dynasty (1368-1644), the scholar Zhu Zaiyu worked out from the changes in methods of calculation the perfect balance of the pitch relationships between the 12 Lu and the precise ratio between each one. He published his discovery, which was about a century before similar discoveries in the western countries in 1584, in a book called A New Treatise on Music. But because of the limitations of the techniques of making musical instruments at that time, his discovery could not be applied in practice, its revolutionary implications were not grasped, and it gradually sank into oblivion. From the perspective of musical theory, this discovery should have marked the transition from ancient to modern music, but Chinese music only entered the modern era 300 years after Zhu Zaiyu's time.