A historical period that serves as a bridge between ancient times and the modern era, characterized by feudal systems, and recognized in Japanese history mainly through the Kamakura and Muromachi periods.

A time frame in Western history stretching from the fall of the Western Roman Empire in the 5th century to the Renaissance and Reformation of the 14th to 16th centuries, often referred to as a period of cultural stagnation and social upheaval, sometimes labeled as the Dark Ages.

In Japanese historical context, this term specifically denotes the period which is divided into early and late phases, with the late phase transitioning into the modern age, while the early phase encompasses significant feudal developments.