during the yamato period, japan had intense naval interaction with the asian continent, largely centered around diplomacy and trade with china, the korean kingdoms, and other mainland states, since at latest the beginning of the kofun period in the 3rd century. according to the "kojiki" and "nihon shoki", empress jingū is claimed to have invaded korea in the 3rd century, and to have returned victorious after three years. whether japan actually ruled a part of korea in ancient times is debated.