What conditions should the concubinage culture in ancient China meet?

The system of concubinage in ancient China was so strict that it was impossible for ordinary people to concubinage. Only dignitaries can do this. I can't accept it if I want to. There have been clear laws and regulations throughout the ages.

Concubine refers to the little wife, the wing room, commonly known as the little wife. In ancient times, men were allowed to marry little wives. Officials and wealthy families have many wives and concubines. It is an honor for a man to marry a concubine, so-called "a gentleman has three wives and four concubines".

Although Yu Ji was hired by the media, she could only enter the door in a small sedan chair, controlled by her first wife and despised by others. Although monogamy was stipulated in the Republic of China, on the basis of private ownership of the means of production, various disguised polygamy still existed.

When the official and the rich saw that the daughter of the poor family was slightly beautiful, they took it as a wife and concubine. If Ming Na fails, he will fight against powerful disciples and rob their relatives to get their lewd pleasure, and he will never stop until he reaches his goal.