Silk built modern Japan, and the hills of Gunma prefecture were its engine room. In the second half of the nineteenth century, farmhouses across this region raised silkworms on the upper floors, and the quality of the cocoons decided the fortunes of families and, eventually, of the nation's exports. At the Takayama-sha site in Fujioka, a farmer named Takayama Chōgorō developed a method of raising silkworms that balanced ventilation and temperature, and he trained students from across Japan in his large farmhouse. You can still see the building, with its distinctive roof vents running along the ridge, designed to let warm, moist air escape.
It is one of four components of the UNESCO World Heritage site of the Tomioka Silk Mill and Related Sites, listed in 2014. The mill itself, in nearby Tomioka, was founded by the Meiji government in 1872 with the help of French engineers and was one of the first large modern factories in Japan. Its long brick buildings, a blend of Japanese and Western techniques, are remarkably well preserved and are the obvious next stop. The story of the young women who came to work there, learning to reel silk on French machines, is told in the exhibitions.
The surrounding country is a pleasant mix of rice paddies, mulberry fields, small towns and wooded hills, with the jagged peaks of Myōgi rising to the west. The Arafune cold storage site, another part of the heritage group, sits in the hills near Shimonita, where natural cold air flowing from rock crevices was used to store silkworm eggs.
The riding is excellent in the hills. The roads around Mount Myōgi are narrow and twisting, with sharp bends, rock faces and dense forest, and views of the strange, eroded peaks. Further west, the old Usui pass road towards Karuizawa climbs through 184 bends, passing the Megane-bashi, a brick railway viaduct built in the Meiji era. Traffic is light on weekdays, though the passes attract riders and drivers at weekends. Watch for fallen leaves, moss and gravel on the narrow roads.
Fujioka has fuel, supermarkets and restaurants. Try Shimonita's famous thick leeks and konnyaku, a specialty of the area, if you pass that way. Summers are hot and humid; spring and autumn are the best seasons for riding. Remember to drive on the left and carry the correct international driving permit.