Nine-rank system

The nine-rank system, also known as the nine-grade controller system, was used to categorize and classify government officials in Imperial China. Created in the state of Cao Wei during the Three Kingdoms, it was used until the Song dynasty, and similar ranking systems were also present in the Ming dynasty and Qing dynasty.

Prior to the nine-rank system, official positions were denoted by their salary paid in number of bushels of grain. For example, during the Han dynasty, the highest-ranking officials were classed as wandan (萬石), meaning ten thousand bushels, and were paid 350 bushels of grain per month. The lowest ranking petty subofficials were paid in pecks, worth less than 100 bushels per year.

A similar system was also used in Korea. In Japan, the Twelve Level Cap and Rank System was adopted in 603 during the reign of Empress Suiko.