At first the goho was the system for the agricultural community in the county, however, in the Heian period, each bo (a unit of administrative district in the Heian period) was divided into four ho (a unit of jobosei [a series of avenues running at right angles to each other]) and, moreover, each ho was composed of four cho (a unit of distance) in Heiankyo (ancient capital in current Kyoto).
当初は地方の農村を対象とした制度であったが、平安時代に入ると平安京の中で各坊を4つの保に分割して更に各保を4町とした。