The Western Zhou Dynasty implemented the system of enfeoffment. Under the emperor, there is a man and a fifth-class title, and the duchess of the emperor is in charge of the office. Therefore, when the princess gets married, the wedding is presided over by the duke who is closely related to the emperor. Because it was the wedding of the emperor's daughter presided over by the duke, the emperor's daughter was later called the princess. I didn't make this up. This has been the case in history. I also think this statement is a bit far-fetched, but there is no other explanation.
Later, the princes competed for hegemony, and the Zhou family declined. The daughter of the princes was called the princess. Later it became the name of the emperor's daughter. But there is a difference between a princess and a princess. For example, a princess is usually the emperor's daughter, but princess royal is the emperor's sister. And the treatment between princesses is different. The ancient princesses always had their own Tangmuyi, that is, the emperor would give the princesses the tax of a certain place to eat, drink and have fun, but unlike the fief, the princesses did not participate in the management of the place. Before the Yuan Dynasty, princesses all had their own Tang Muyi, but the sizes were different.
Generally speaking, Tang Muyi has three levels: county, county and township. The emperor's daughter usually has Tang Muyi in a county or county, and the daughter of the prince is mostly a countryman. But different dynasties and generations have different systems, and they are all the daughters of the emperor. The emperor can be rewarded more if he is happy. Since the Yuan Dynasty, there was no Tang Dynasty as a princess, but the monthly salary was paid directly by the Ministry of Internal Affairs and other institutions.
In addition, not all princesses will marry noble families. In the Ming Dynasty, in order to prevent consorts from interfering in politics, all princesses married civilians. So many rich people will pay bribes to eunuchs who are responsible for choosing husbands.