Gunma was joined with Tochigi Prefecture and called Kenu Province. This was later divided into Kami-tsu-ke (Upper Kenu, Gunma) and Shimo-tsu-ke (Lower Kenu, Tochigi). The area is sometimes referred to as Jomo (??, Jomo). For most of Japanese history, Gunma was known as the province of Kozuke.

In the early period of contact between western nations and Japan, particularly the late Tokugawa, it was referred to by foreigners