The Republic of China (ROC), commonly recognised as the official designation of China from 1912 to 1949, was a country in East Asia based in Mainland China, prior to the relocation of its central government to Taiwan as a result of the Chinese Civil War. At a population of 541 million in 1949, it was the world's most populous country. Covering 11.4 million square kilometres (4.4 million square miles), it consisted of 35 provinces, 1 special administrative region, 2 regions, 12 s…

Various names for the island of Taiwan remain in use, each derived from explorers or rulers during a particular historical period. The name Formosa (福爾摩沙) dates from 1542, when Portuguese sailors sighted an uncharted island and noted it on their maps as Ilha Formosa ("beautiful island"). The name Formosa eventually "replaced all others in European literature" and remained in common use among English speakers into the 20th century.