Japan and its Chinese and European worlds,
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.
To the north of Honshu (and in the adjoining Tohoku, or north—east of Honshu itself) the climate was influenced by the frontier of cold and hot currents and winds on the interface of the world's largest landmass and its largest ocean. Cold currents pushing down along the coast of Siberia in meeting the upward—moving warm currents of the Pacific resulted in both pervasive fog and in sudden winter storms. As the summer monsoon weakened, the winds of the Siberian landmass, pushing out into the Pacific in a great anti—cyclonic sweep, curled in from a northeasterly direction. On their path, they met the moisture—laden air of the Pacific: in summer precipitation was heavy if they pushed out prematurely, and in winter snow lay deep on the ground in both the Ezo islands (of which the principal one, Ezo—ga-shima, was renamed Hokkaido 18