During the 4th century AD, (
Kofun period) the area of modern Gunma and Tochigi prefectures were known as , literally "hairy field", but used as
ateji for or "food field" in reference to an imperial agricultural area. At some unknown point in the 5th century, the area was divided at the
Kinugawa River into ("Upper Keno") and ("Lower Keno"). Per the
Nara period Taihō Code, these provinces became and . At some point, the
no meaning "field" was reanalyzed as the possessive particle
no, resulting in shortened names (without the or "province" portion) of
Kamitsuke and
Shimotsuke. In 713, with the standardization of province names into two
kanji, these names became and . Later regular sound changes caused
Kamitsuke to shift to
Kaudzuke, and then to modern
Kōzuke. During the
Heian period, from the year 811, Kōzuke (along with
Hitachi and
Kazusa) was one of the three provinces where an Imperial Prince was designated as nominal ruler. The area was noted for its production of horses. The original capital of the province was located in what is now
Maebashi, along with the
kokubun-ji and the
sōja of the province. The
ichinomiya was located in what is now the city of
Tomioka. During the
Sengoku period, Kōzuke was contested between the
later Hōjō clan, the
Takeda and the
Uesugi clans. After the establishment of the
Tokugawa Shogunate, much of the province was assigned to several
feudal domains. The
Nakasendō and the
Mikuni Kaidō highways passed through the province, and numerous
post stations were established. Following the
Meiji restoration, the various domains became prefectures with the
abolition of the han system in 1871. These various prefectures merged to form Gunma Prefecture in 1876. The area subsequently prospered with the development of sericulture and silk spinning industries. ==Historical districts==