I learned about Danjo-dai in history class.

It is difficult to find the answer to this big question.

The Heian period was a time when Japanese culture developed greatly.

The Azuchi-Momoyama period was a very important time in Japanese history.

The Azuchi-Momoyama period, also known as the Oda-Nobunaga period, was a very important time in Japanese history.

The Ashikaga era is a part of Japanese history.

The Kamakura period was a very important time in Japanese history.

The ruins from the Kofun Period are important for a deep understanding of Japanese history.

The Muromachi period is a part of Japanese history, a time when many cultural changes occurred.

The Asuka Period is a part of Japanese history, a time when culture and arts greatly developed.