The Nanboku-chō period (南北朝時代, Nanboku-chō jidai), also known as the Northern and Southern Courts period, was a period in Japanese history between 1336 and 1392, during the formative years of the Muromachi (Ashikaga) shogunate. During this time, two opposing Imperial courts and their respective claimants as Emperor were engaged in conflict over their claims to the Chrysanthemum Throne, with the Southern Court ultimately renouncing their claim in favor of the Northern Court in 1392. This period became a source of contention for many Japanese historians and scholars over the following centuries. Initially, the North's victory in the dispute led official histories to paint them as the legitimate claimants. In reality, the Northern pretenders were simply puppet rulers under the direct control of the Kamakura and Ashikaga shogunates, while the Southern claimants maintained control of the Japanese Imperial Treasures, the sacred artifacts that confirmed an Emperor's legitimacy. To officially resolve this historical dilemma, in 1911 Emperor Meiji issued an edict that the Emperors of the Southern Court were the legitimate claimants during this period.
The destruction of the Kamakura shogunate of 1333 and the failure of the Kenmu Restoration in 1336 opened up a legitimacy crisis for the new shogunate. Institutional changes in the estate system (shōen) that formed the bedrock of the income of nobles and warriors altered the status of the various social groups. The establishment of the Ashikaga shogunate broadened the economic base of the warriors, while undercutting the noble proprietors. However, this trend had started already with the Kamakura bakufu.