From time immemorial, rulers of small sates have sought to maintain friendly relations with one another. We, the Great Mongolian Empire, have received the Mandate of Heaven and have become the master of the universe. […] From now on, let us enter into friendly relations with each other. Nobody would wish to resort to arms.
This letter to Japan by Kublai Khan was a veiled threat of war unless Japan acknowledged the Mongol Empire and paid tribute. The Japanese however sent back this envoy to Koryo Korea. Kublai Khan would try again to send an envoy to Japan in 1268 but it too would be ignored. With the Southern Song Dynasty still benefitting greatly from the trade between themselves and Japan, Kublai Khan began to create a massive fleet of ships in 1268 through the Koryo Korea ship yards and also enlisted many Korean troops. Koryo Korea was a peninsula, thus it had developed naval capabilities, so the occupation of Koryo Korea by the Mongols played a key role in the resources needed to invade Japan. In 1269 Koryo Korea descended into civil war and Kublai Khan took this opportunity to further strengthen his hold on Koryo. After strengthening his grasp on Koryo, Kublai Khan requested that Japan recognize