This essay suggests that the roots of the geopolitical power scheme of the Korean peninsula lie not in the time around the end of the Korean Empire but earlier, in the time of the “Bellum Corai” (Japanese-Korean War of 1592). It also suggests that the open and integrated character of the present-day Korean people springs from the historical conditions that made it necessary for them to reflect both the interaction and the conflict between Eastern and Western civilizations, despite the fact that these “historical conditions” led us through the pain of colonial fetters and national division. In considering this, this essay analyzes some newly discovered letters of Jesuits missionary-priests who reported on the Bellum Corai in letters and reports to their colleagues in Europe.