In modern Japan, during the period between 1868 and 1945, the terms “Toyo,” “Toa,” “Toho,” “Higashi Asia,” and “Asia” were employed to mean “the East” or “the oriental”; while “Rugaku,” “Rukyou,” “Kangaku,” and “Shinagaku” were used to convey the cocept of “Confucian studies,” the study of a foreign system of thought. These terms, which have different meanings and different concepts of civilizations, and are taken from different historical backgrounds, reflect Japanese ways of understanding China, showing the different viewpoints and methodologies of researchers. These terms have significantly different implications in their different contexts, and these implications have not been well explored. Therefore, this article discusses the context of “Toyo”, “Toa,” “Jyukyo,” or “Jyugaku” discourses in the early 19th century from the perspective of intellectual history. In brief, the concept of “Toyo” means the wider territory of Asia in the early 19th century, including China, Japan and India, three countries that from the area on which “Toyo Tetsugaku” discourses are based. The concept of “Toyo” becomes narrower in the twentieth century, covering only China, Japan and Korea, three countries that are the subject of “Toyo Rinri” and “Toyo Bunka.” “Toa” discourse appeared in the 1920s as a discourse dealing with China, Japan, and Korea. With the strategic military expansion of Japan in the period between the 1930s and the 1940s, the term “Dai toa” was then used to cover the even lager area of Manshuria, India, and South Asia. “Kangaku”, a term which had already appeared in the late 18th century, is a neological substitute for “Kokugaku,” which defines Confucianism as part of foreign learning and culture. “Jyukyo,” advocated by the ruler and conservative Confucians after the mid-Meiji period, emphasizes moralism and loyalty for the emperor and the nation. “Jyukyo” was widely used as a conceptual tool for education, and its extension was later referred to as “Koshikyou”. In contrast, “Shinagaku” as a methology of “Sinology” conveys an attitude of pursuing knowledge independently and scientifically; and so is independent from the confines of political ideology. As we consider the beginning of “Confucian Studies in East Asia” from a Taiwanese perspective, the hitorical changes of terminologies summarized above can serve as a mirror to reflect related information. The disappearance of the terms “Toyo” and “Toa,” together with the decline of “Jyugaku” and “Jyukyou,” may also lead us to consider more deeply some of the concepts related to modern scholarship on “Confucian Studies in East Asia.”