Kenki is my best friend.

Yoshinori is my best friend.

Kisaburo is my best friend.

Yukinori is my best friend.

The Permian period is one of the most important times in Earth's history.

The culture of the Nara period played a very important role in Japanese history.

During the Ice Age, the climate of the Earth changed significantly.

He survived through the Dark Ages.

This piece of art reflects the zeitgeist of its time.

The Age of Enlightenment was a period when science and reason were emphasized.