First, the "rod" punishment is one of the five punishments.
From a long time ago, people had the concept of punishing mistakes, so they extended the "five punishments". The "five punishments" are divided into ancient five punishments and feudal five punishments. The five punishments in ancient times, also known as the five punishments of slavery, include "Mo, Mo, Mo, Gong and Da Bi"; The five feudal punishments include "slap, stick, exile and execution".
Second, there is a strong sense of humiliation.
In ancient times, people paid great attention to courtesy, justice and honesty. When flogging, that is, spanking as the saying goes, they will tear off the prisoner's trousers in advance and then give him a fat beating on his ass. This is undoubtedly a great insult to prisoners and has played a double punishment role in their body and mind.
Third, the birth of "Tang Ming Acupuncture Map". During his stay in Li Shimin, Emperor Taizong accidentally saw this map of acupuncture and moxibustion in Tang Ming from the doctor too much. Through this photo, he learned the truth about the human body. Most of the important organs of the human body are in the chest and back. If these parts are severely hit, they are likely to be life-threatening, while the acupoints on the buttocks are relatively few and relatively safe. That's why Li Shimin stipulates that prisoners who have been clubbed can only be spanked.