The Han sphere, including Vietnam, Korea, Japan, Taiwan and China, adopted Han characters and classical Han writing as the official written language before the 20th century. However, great changes came with the advent of the 20th century. After World War II, Han characters in Vietnam and Korea were officially replaced by the romanised "Chu Quoc Ngu" and phonemic Hangul, respectively. In Japan, the number of Han characters in use decreased, and the syllabic "Kana" system was promoted to a national status. In Taiwan, although Taiwanese romanisation was developed centuries ago, Han characters remain the dominant orthography in current Taiwanese society. This paper examines Taiwan's orthographic transition from the perspective of the Han sphere. Both internal and external factors have contributed to the different outcomes of orthographic reform in these countries. Internal factors include the general public's demand for literacy and anti-feudal hierarchy. External factors include the political relationships between these countries and the origin of Han characters (i.e. China). (Contains 5 notes.)