China's writing system was originally arranged vertically from right to left and from top to bottom. Before the May 4th Movement, all the books in China were.
Horizontal arrangement is brought by the habit of horizontal writing in Europe and America; After the Westernization of Meiji Restoration in Japan, it gradually changed to horizontal arrangement, which influenced the cultural circles in China and Taiwan Province Province, which belonged to Japanese territory at that time.
In the early days when the National Government moved to Taiwan, civil servants still used the habit of marking official documents with a brush. During the Chinese cultural renaissance, the government even stipulated that all straight books should be used, and the signboard documents were from right to left. In 1980s, the entry and exit control in Taiwan Province Province was abolished, and people frequently communicated with foreign countries, which brought great trouble to communication. People began to write on the left when they arranged horizontally. In the left book, more and more shop signs and company documents were arranged horizontally because Chinese and English were juxtaposed. There is no official ban, which means that left and right books are ok, but straight row is still the official position.
Until the mid-1990s, newly established drama newspapers began to adopt horizontal layout, and more and more newspapers and publishing industries followed suit. In 2003, the government officially changed Zuo Shu's official documents from vertical to horizontal as the official standard. However, some traditional newspapers, such as United Daily News and China Times, still maintain vertical layout, as do some collections of poems and essays that want to maintain beautiful words.
The Japanese experience is similar to that of Taiwan Province Province. If you look through several major Japanese newspapers, you can also see the straight edition.