The correct answer is the following.
Japan’s cultural and economic relationship to China and Korea were basically in the cultural-arts aspect, more than politically or economically. In Medial times, Japan received the influence of the Buddhist doctrine, in writing, and other cultural aspects. In the economy, Japan did not totally isolate as was the case of China, but Japan continued to need a relationship with China. The Middle Ages in Japan encompasses three periods: the Asuka, the Narad, and the Heian period. During the Asuka period, Japan developed strong economic ties with Korea, specifically with the Baejek people in the south part of the Korean territory. This is the time when Japan was introduced to Buddhist principles.