In ancient China, people divided the time of one day into twelve periods.

Zi Shi is the first hour of the twelve periods, about 23:00 to 1:00 

Chou Shi is the second hour of the twelve periods, about 1:00 to 3:00 

Yin Shi is the third hour of the twelve periods, about 3:00 to 5:00 

Mao Shi is the fourth hour of the twelve periods, about 5:00 to 7:00 

Chen Shi is the fifth hour of the twelve periods, about 7:00 to 9:00 

Si Shi is the sixth hour of the twelve periods, about 9:00 to 11:00 

Wu Shi is the seventh hour of the twelve periods, about 11:00 to 13:00 

Wei Shi is the eighth hour of the twelve periods, about 13:00 to 15:00 

Shen Shi is the ninth hour of the twelve periods, about 15:00 to 17:00 

You Shi is the tenth hour of the twelve periods, about 17:00 to 19:00 

Xu Shi is the eleventh hour of the twelve periods, about 19:00 to 21:00 

Hai Shi is the twelfth hour of the twelve periods, about 21:00 to 23:00