Gun, only a district's name nowadays, was established in 7th century as a administrative unit of old Japan. Of course, there were the kuni (_??_)and the agata (_??_) before the Taika Kaishin (_??__??__??__??_), but the kuni and the gun were the first local administrative system, and had a new territory with a distinct boundary.
In this article, I intend to clarify the following points about the gun by mean of the analysis of newly builtup guns written down in the Rikkokushi (_??__??__??_), the six chronicle in ancient time, and the reconstruction of some boundaries of the guns in the Heiancho (_??__??__??_), and others.
(1) Almost all of gun's areas were quitely new ones, established by a partition of kunis and agatas, which were to be considered the spontaneous community. Though gun's. boundary followed frequently after rivers, watersheds or woods, at cultivated plains we found many boundaries of straight line by jori-systems (Fig. 2 shows it at the Yamato basin). The gun was therefore the pure institutional community and the formal area.
(2) However, never ignored the gun's area geographical conditions. For example, there were many that it based upon the topographical condition, and had suitable goris (_??__??_) and population for the middle community between the kuni and the gori.
In this point one may say that the gun had a bud to bloom the spontaneous, historical community and the substansive area later days, from the biginning of the formation of the gun.
