Gunma Prefecture

Verified Timeline

Lore & Background

The ancient province of Gunma was a center of horse breeding and trading for the newly immigrated continental peoples (or Toraijin). The arrival of horses and horse tackle coincided with a large migration from the mainland, and the horse became a vital part of Japanese military maneuvers, displacing the older Yayoi tradition of fighting on foot. When Mount Haruna erupted in the late 6th century, Japan was still pre-historical; the Gunma Prefectural archaeology unit in 1994 dated the eruption through zoological anthropology at corral sites buried in ash. In the past, Gunma was joined with Tochigi Prefecture and called Kenu Province, later divided into Kami-tsu-ke (Upper Kenu, Gunma) and Shimo-tsu-ke (Lower Kenu, Tochigi). The area is sometimes referred to as Jomo (上毛, Jōmō). 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 as the 'Joushu States', inside (fudai, or loyalist) Tokugawa retainers and the Tokugawa family symbol is widely seen on public buildings, temples, and shrines.

Reader's Guide

Gunma Prefecture holds significance as a historical crossroads of continental migration and horse culture that shaped Japanese military tactics. Its role in early industrialization is marked by the first modern silk factories built with Italian and French assistance at Annaka in the 1870s. The prefecture was also the site of the Gunma Incident of 1884, a bloody struggle between democratic Westernisers and conservative Prussian-model nationalists, where farmers were said to be the first victims of the Murata rifle. In the twentieth century, aviation pioneer Nakajima Chikushi founded the Nakajima Aircraft Company in Oizumi, which became a world leader in aeronautical design and later produced Subaru motorcars. Gunma is also notable for the Girard incident of 1957, which disturbed US-Japanese relations. Its legacy includes four modern prime ministers, a unique local dialect (gunma-ben or jōshū-ben), and the traditional card game Jomo Karuta. The prefecture is home to eleven of Japan's over thirty Melody roads, and on August 5, 2025, Isesaki recorded a temperature of 41.8 °C, the hottest ever in Japanese history.

Did You Know?

• Gunma Prefecture is one of only eight inland prefectures in Japan.
• On August 5, 2025, Isesaki recorded a temperature of 41.8 °C, the hottest ever in Japanese history.
• Gunma produces over 90% of Japan's konnyaku.
• Four modern prime ministers are from Gunma: Takeo Fukuda, Yasuhiro Nakasone, Keizo Obuchi, and Yasuo Fukuda.
• Gunma is home to eleven of Japan's over thirty Melody roads.