How big is a 'kan'?
By Kim Ji-myungOne big difficulty that researchers of Korean history face is the issue of units. Length, area, weight, volume and time seem to have been measured by a variety of standards, depending on periods and areas.Old records tell us that most unit systems were made in ancient China and spread to Korea and other neighboring countries. In the case of “pyeong” to measure land and field space, it was exported to Japan during the Three Kingdoms period as a unit of 3.158 square meters as used in the ancient Korean kingdom of Goruryeo and Tang China. Later it was introduced back to Korea by Japan as 3.3058m² per unit as standardized in Japan in 1874.The “ja” or “cheok” is a unit of length like a foot in the West. Just as with any unit system, the ja is divided into smaller units, in this case 10, called “chon.” Before the Goryeo period, roughly until the 10th Century, countries had different standard unit lengths which were recorded as Han Chinese unit, Tang unit or Goguryeo unit. However during the Joseon period (