Kei (a unit of area) (頃)
"Kei"or qing is a unit of area used in the Chinese traditional system of measurement (unit system).
1 qing equaled to 100 mu (Chinese area unit) and 1 mu was 120 times as large as 5 square chi (And in ancient times, mu was 100 square bu.)
In 1929 after the establishment of the Republic of China, the decimal system was introduced into the measurement unit system.
Although 1 mu was redefined as 1/15 hectares to slightly change the volume, 1 qing covered approximately 6 hectares in general. In modern China, since the same character "頃" is used to represent "hal," they distinguish qing in the traditional unit system from "hal" by writing quing as "市頃" while "ha" as "公頃."