The Nanboku-chō period ("South and North courts period", also known as the Northern and Southern Courts period), spanning from 1334 to 1392, is a period that occurs during the formative years of the Muromachi bakufu of Japan's history.The Imperial seats during the Nanboku-chō period are in relatively close proximity, but geographically distinct.

They are conventionally identified as: Northern capital : Kyoto Southern capital : Yoshino.During this period, there exists a Northern Imperial Court, established by Ashikaga Takauji in Kyoto, and a Southern Imperial Court, established by Emperor Go-Daigo in Yoshino.Ideologically, the two courts fight for fifty years, with the South giving up to the North in 1392.

However, in reality the Northern line is under the power of the Ashikaga shoguns and has little real independence.Since the nineteenh century the Emperors of the Southern Imperial Court have been considered the legitimate Emperors of Japan.

Other contributing factors are the Southern Court's control of the Japanese imperial regalia, and Kitabatake Chikafusa's work Jinnō Shōtōki, which legitimizes the South's imperial court despite their defeat.The consequences of events in this period continue to be influential in modern Japan's conventional view of the Tennō Seika (Emperor system).

Under the influence of State Shinto, an Imperial decree dated March 3, 1911 established that the legitimate reigning monarchs of this period were the Southern Court.

After the Second World War, a series of pretenders, starting with Kumazawa Hiromichi, claim descent from the Southern Court and challenge the legitimacy of the modern imperial line, which is descended from the Northern Court.The destruction of the Kamakura shogunate of 1333 and the failure of the Kemmu Restoration in 1336 opes up a legitimacy crisis for the new shogunate.

Furthermore, institutional changes in the estate system (the shōen) that form the bedrock of the income of nobles and warriors alike decisively alters the status of the various social groups.

What emerges from the exigencies of the Nanboku-chō (Southern and Northern Court) War is the Muromachi regime, which broadens the economic base of the warriors while undercutting the noble proprietors, a trend that had started already with the Kamakura bakufu.