Chuko (periodization) (中古 (時代区分))
Chuko (Middle Ages) is a word used to represent a time period, and is the second of the three words: joko (ancient times), chuko (middle ages), and kinko (early modern age).
Chuko carries the same meaning as the "Middle Ages." In Japanese literary history, the word chuko is used in the 'Chuko Rokkasen' (six Japanese poets presented in the prelude of Kokinshu, A Collection of Ancient and Modern Poetry in the early Heian period) and the 'Chuko Sanjurokkasen' (Thirty-six Japanese poets of Nochi no Rokurokusen selected by FUJIWARA no Norikane). Chuko is therefore regarded as a word used to refer to the Heian period (794 - 1192) in Japanese literature. On the other hand, Japanese literature also uses the term 'chusei' to refer to the time period after the Kamakura period which has the same meaning as chuko, and the appropriateness of this practice has been questioned.
It is for this reason that there is a tendency to avoid the use of the word 'chuko.'