Gunma Prefecture is a prefecture of Japan located in the northwest corner of the Kantō region on Honshū island. Its capital is Maebashi. The remains of a Paleolithic man were found at Iwajuku, Gunma Prefecture, in the early 20th century and there is a public museum there. Japan was without horses until around the early centuries AD, and present-day Gunma was a center of the horsebreeding and trading activities when continental peoples and Japanese began a strong trade in the animals. When Mt Haruna erupted in the late 6th century Japan was still in pre-history, but the Gunma Prefectural archaeology unit in 1994 was able to date the eruption through zoological anthropology at the corral sites that were buried in ash. In the past, Gunma was joined with Tochigi Prefecture and called Kenu Province. This was later divided into Kami-kenu (Upper Kenu, Gunma) and Shimo-kenu (Lower Kenu, Tochigi). The area is sometimes referred to as 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 as the "Joushu States", inside (fudai, or loyalist) Tokugawa retainers and the Tokugawa family symbol is widely seen at public buildings, temples and shrines. The first modern silk factories were built with Italian and French assistance at Annaka in the 1870s. In the early Meiji period, a bloody political struggle between idealistic democratic westernizers and conservative Prussian-model nationalists took place in Gunma and neighboring Nagano.