In 1391, at Meitoku War, Yoshimitsu weakened the Shugo daimyo (military governor turned daimyo), the Yamana clan and took complete control of the Samurai forces, and then started serious negotiation with the help of Yoshihiro OUCHI, who was military officer of Izumi Province, Kii Province and who had private estate next to the Southern Court.
1391年（明徳2年/元中8年）の明徳の乱で有力守護大名の山名氏を弱体化させ、武家勢力を統率した義満は、和泉国・紀伊国の守護で南朝と領地を接する大内義弘の仲介で本格的交渉を開始した。