Ancient East Asia was dominated by the three states known today as China, Japan, and Korea. These kingdoms traded raw materials and high-quality manufactured goods, exchanged cultural ideas and practices, and fought each other in equal measure throughout the centuries. The complex chain of successive kingdoms in all three states has created a rich web of events that historians have sometimes found difficult to disentangle; a situation not helped by modern nationalist claims and ideals superimposed on antiquity from all three parties. As the historian Kim Won-Yong put it, "Korea acted as a cultural bridge between China and Japan" (Portal, 20). Historians continue to discuss whether that bridge was one-way or two-way traffic and, if the former, which direction, but suffice to say that there was such a bridge, and its consequences in art, politics, and history in both countries still resonate today.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/982/ancient-korean--japanese-relations/.