The Oei rebellion, which broke out in the sixth year of the Oei era (1399) during the Muromachi period, was a revolt against the Muromachi bakufu (Japanese feudal government headed by a shogun) led by the shugo daimyo (feudal lord) Yoshihiro OUCHI, in which he occupied the city of Sakai (modern-day Osaka) which was eventually brought to ruin.
応永の乱（おうえいのらん）は、室町時代の応永6年（1399年）に、守護大名の大内義弘が室町幕府に対して反乱を起こして堺市に篭城して滅ぼされた事件である。