Here's why:
* China: The mid-500s in Japan was marked by the Asuka period, a time of intense cultural exchange with China. This exchange was driven by Buddhism, which was introduced to Japan from China in the 6th century. Buddhism brought with it not only religious practices but also Chinese art, architecture, literature, and philosophy, heavily influencing Japanese art, literature, and social structure.
* Korea: While less impactful than China, Korea also played a crucial role in cultural transmission to Japan. Korea acted as a bridge for Chinese influence, with many cultural elements passing through Korea before reaching Japan.
The mid-500s saw the establishment of Buddhism in Japan, leading to the construction of temples and the creation of religious art. It also saw the development of a new writing system based on Chinese characters, contributing to the development of Japanese literature. These developments solidified a significant cultural shift in Japan, heavily influenced by China and, to a lesser extent, Korea.