In the port opening period, Korea was included in the Western-oriented international order of law and confronted foreign powers’ invasion. Korea desperately needed knowledge about Western diplomacy and modernization, which could be gained via knowledge of Western history. Taesŏ-sinsa (A New History of the Western World) was a Western history book published in this period. Originally written by the British in 1880 as the title of The 19th Century: A History, Taesŏ-sinsa was translated into Chinese in 1895 by a British missionary, and in 1897 Korean Hakbu (Ministry of Schools) published the Korean translation. The main contents of Taesŏ-sinsa can be summarized as the ‘New Law’ theory (Reform theory). Taesŏ-sinsa developed international politics theory and spread the concept of antiwar peace theory, international law, international arbitration, and international opinion etc. Taesŏ-sinsa’s New Law theory spread modern reformation to Koreans in the Confucian People-Oriented (Minbon) words like 'appease the people (Anmin)' and 'foster the people (Yangmin)'. Taesŏ-sinsa’s ‘New Law’ theory helped the Enlightenment Party’s opinion to persuade the Koreans effectively, who shared Confucian sensibility. Also, this progress served as momentum for People-Oriented thought, which was the main political idea in the Chosŏn dynasty, transforming into modern Democratic thought.