When faced with the threat of invasion by the Mongol Empire and Goreyo, its vassal state, Kamakura Japan could have followed a diplomatic course with the Mongols or formed an alliance with anti-Mongol forces on the continent. Authorities in Japan, however, rejected both options, choosing instead to fight the Mongols alone on their own soil. International-relations models fail adequately to explain Kamakura Japan’s preference for self-reliance. By contrast, Asuka Japan, when faced with a similar invasion from Tang–Silla forces in an earlier era, opted to form an alliance with Baekjae, which culminated in a battle on the continent. Despite the copious scholarly treatment of the Mongol invasion, an important question about the Mongol–Japan War remains unanswered: How and why did Kamakura Japan’s governmental structure incline it to choose defensive self-reliance rather than diplomacy or military alliance?

当面对蒙古帝国及其附庸国高列的入侵威胁时，镰仓日本本可以与蒙古人走上外交路线，或者与大陆上的反蒙古势力结盟。然而，日本当局拒绝了这两种选择，而是选择在自己的土地上单独与蒙古人作战。国际关系模型未能充分解释镰仓日本对自力更生的偏好。相比之下，日本明日香在更早时期面临唐新罗军队的类似入侵时，选择与百济结盟，最终在大陆上进行了一场战斗。尽管学术界对蒙古人的入侵进行了大量研究，但关于蒙日战争的一个重要问题仍未得到解答：