Classical Japan

During the Asuka period (538 to 710), the proto-Japanese Yamato polity gradually became a clearly centralized state, defining and applying a code of governing laws, such as the Taika Reforms and Taihō Code.^[12] Also during the same period, the Japanese developed strong economic ties with the Paikche or Baekje people, who lived on the southwestern coast of the Korean Peninsula. Good relations with the Baekje had begun in 391 when a Japanese expedition saved the King of Baekje and the Baekje people from their traditional enemies—the Koguryo people—who lived in the northern part of the Korean Peninsula.^[13]
Indeed, Buddhism was introduced to Japan in 538 by Baekje people, to whom Japan continued to provide military support.^[14] In Japan, however, Buddhism was promoted largely by the ruling class for their own purposes^{[citation needed]}. Accordingly, in the early stages, Buddhism was not a popular religion with the common people of Japan.^[15] However, the introduction of Buddhism led to a discontinuing of the practice of burying deceased people in large kofuns.
Prince Shōtoku came to power in Japan as Regent to Empress Suiko in 594. Empress Suiko had come to the throne as the niece of the previous Emperor—Sujun (588–593)--who had been assassinated in 593. Empress Suiko had also been married to a prior Emperor—Bidatsu (572–585), but she was the first female ruler of Japan since the legendary matriarchal times.^[16]
As Regent to Empress Suiko, Prince Shotoku devoted his efforts to the spread of Buddhism and Chinese culture in Japan.^[16] He is also credited with bringing relative peace to Japan through the proclamation of the Seventeen-article constitution, a Confucian style document that focused on the kinds of morals and virtues that were to be expected of government officials and the emperor's subjects. Buddhism would become a permanent part of Japanese culture.
A letter brought to the Emperor of China by an emissary from Japan in 607 stated that the "Emperor of the Land where the Sun rises (Japan) sends a letter to the Emperor of the land where Sun sets (China)",^[17] thereby implying an equal footing with China which angered the Chinese emperor.^[18]