China helped strengthen Buddhism, while Buddhism helped strengthen Japan. Buddhism, had cultivated and grown very different since the time when it was introduced to China in the 6th century B.C. and since it had entered Japan in 552 A.D. Japan had fallen behind China; China was more advanced and developed in the arts, culture, economics, etc. Buddhism, which originated in India, soon found it's way to China, where it soon spread because of China's influence and dominance on other countries. Monks went through Korea to Japan spreading the religion and converting people along their journey.
China had strengthened Buddhism. When Buddhism came to China, Buddhism was not powerful or known. China was advanced and it had traits that strengthened Buddhism in theory and practice.
Over the years, as Buddhism began to cultivate and break into many different sects, it soon spread to Japan. Japan at this time was not very advanced, and had nothing that could strengthen Buddhism. But, Buddhism however, had been strengthened by China and was very powerful. The missionaries that brought Buddhism to Japan were from China. To make it possible for the Japanese to practice Buddhism, they would have to be taught several skills, and many tapestries and documents had to be brought over from China. They had to be taught so that they could practice Buddhism. Also, as the missionaries transported the documents, they brought over Chinese culture and style. Eventually, the Japanese capital was in the form of the Chinese capital. Buddhism made the Japanese more modern, and it brought Chinese culture into Japan.