Obviously Mongolia is not part of China, but Kublai Khan did twice try to invade Japan. Typhoons scuppered both chances (and from which the Kamikaze tradition w

Obviously Mongolia is not part of China, but Kublai Khan did twice try to invade Japan. Typhoons scuppered both chances (and from which the Kamikaze tradition was born). For most of Japan's history they have had an isolationist stance to the outside world. Obviously this was not the case from between Commander Perry and the end of World War II. With respect to China, for hundreds of years Japan was considered a quasi-vassal state to various Chinese Emperors.