Japan in the sixteenth century was an archipelago of which the main component was a large island (Honshu) separated from three middle-sized islands (Kyushu, Shikoku and Ezo) by narrow straits. It was already in physical and human terms a remarkably isolated country. To the west, it faced two inward-looking countries, one the great landmass of China, the other the Korean peninsula whose proximity to Japan made it the vehicle of contact with China. To the east lay the enormous north Pacific ocean, little explored until the late eighteenth century. Cultural influences (Confucian philosophy and Japan's writing system, both Chinese in origin, and the Buddhist religion itself) had all been transmitted through Korea more than a thousand years previously, by a small elite body of monks, scholars and noblemen, some of them returning Japanese. Later contact was fitful, and at the end of the sixteenth century, there was little trade and even less cultural movement between Korea and Japan. However, unsettled international conditions would give Korea, in the seminal decade of the 1590s and again after 1868 in the troubled times of renewed western encroachments in Asia, an importance transcending existing isolation. Isolation to the east and west was reinforced by an absence of contacts to the north, accounted for by climatic conditions, and to the south, created by economic circumstances.