The Ouchi clan had become so powerful - simultaneously shugo of six provinces, Suo, Nagato, Iwami, Buzen, Izumi, and Kii, and possessing great wealth thanks to their trade - that they were bound to put Yoshimitsu, who was aiming to establish a system of despotic rule by the Shogun, on his guard.
周防・長門・石見・豊前・和泉・紀伊の6カ国の守護を兼ね貿易により財力を有する強大な大内氏の存在は将軍専制権力の確立を目指す義満の警戒を誘った。