The keze 科則 regulations for the classification of land took into consideration the fertility of the land to fix the appropriate field tax rate. A similar procedure is described in the report on the tributes delivered by the provinces of China to Yu the Great 大禹 (Shangshu 尚書, ch. Yugong 禹貢), and also in the history book Guoyu 國語, where the soil classification method in the regional state of Qi 齊 is briefly mentioned.
During the Later Han period 後漢 (25-220 CE), the governor (taishou 太守) of the commandery of Shanyin 山陰, Qin Peng 秦彭, used to have the fields in his commandery classified into three classes (pin 品). The tax systems applied between the Wei 曹魏 (220-265) and the Tang 唐 (618-907) periods also factored the soil quality into the tax rate. The term keze was first used during the Song period 宋 (960-1279). It was much more detailed than before and made use of 5 grades of quality. The Jin dynasty 金 (1115-1234) in northern China used even 9 classes.
The Ming dynasty 明 (1368-1644) used 11 grades for official fields, and 10 for private fields, but ownership often changed and made the system particularly complex to apply, mostly in the lower Yangtze region. The lowest tax rate of the early Ming period was 3 he 合 1 shao 勺 (per mu 畝 of land, see weights and measures), and the highest 7 dou 斗 5 sheng 升 or even 1 shi 石 per mu. Because of the very complex situation, the grand coordinator (xunfu 巡撫) of Jiangnan 江南, Zhou Chen 周忱 (1381-1453), proposed in 1433 the introduction of an adjusted tax system called pingmifa 平米法. The tax load of heavily taxed field owners was lifted, and the owners allowed to deliver the greater part of their taxes in money (zhese 折色), while the tax load of lowly taxed field owners increased, and they had to deliver the greater part of their taxes in kind (bense 本色), i.e. in rice. At the same time the tax difference between public fields and private fields was abolished, and from both, the common transport-loss surcharge (hao 耗) was levied.
In the late Ming period the common classification pattern consisted of 3 classes and 9 grades (sandeng jiuze 三等九則). Yet not all districts followed this pattern during the Qing period 清 (1644-1911). Kunshan 昆山, Jiangsu, for instance, continued to use 59 grades, and Huating 華亭 56 grades. Accordingly, the chapter on field classification (Tianfu keze 田賦科則) in the Administrative Statutes Qing huidian 清會典 gives detailed information on the variety of local systems. Classification systems continued until the end of the Republican period in 1949.