Shikoku

The smallest and least populated of the four main islands, separated from Honshu by the Inland Sea and, until 1988, reachable only by boat. That isolation is the region's defining fact. Mountains run east to west across the middle, so even internal movement was difficult, and the four historic provinces developed with their backs to each other; the modern prefectures still have poor connections between them. The island's most famous institution is the Shikoku pilgrimage, a circuit of eighty-eight Buddhist temples associated with Kukai, the ninth-century monk who founded Shingon Buddhism and was born there. Walking the full circuit takes six weeks and predates any comparable European pilgrimage route in continuous use. Tokushima's indigo made the eastern province wealthy in the Tokugawa period, and Kochi on the southern coast, isolated behind mountains and facing the open Pacific, produced Sakamoto Ryoma and much of the third faction that overthrew the shogunate alongside Satsuma and Choshu. The Inland Sea coast was a pirate and shipping zone for centuries, controlled by the Murakami fleets. Depopulation is now the region's central problem: Shikoku has among the oldest populations and steepest declines in Japan, with whole villages abandoned. The three bridge systems built between 1988 and 1999 to connect it to Honshu were extraordinarily expensive and did not reverse that. The Naruto whirlpools and the Iya valley vine bridges draw what tourism there is. Matsuyama's Dogo Onsen is one of the oldest hot springs in Japan. The island has no Shinkansen line. Its four prefectures together hold fewer people than the city of Yokohama. Sanuki udon is Kagawa's export.

• Existed: 800 CE – present
• Type: Entity