As far as the ancient service agencies are concerned, the most obvious ones are the various departments in the palace. Take the Ming Dynasty as an example. In the Ming Dynasty, the imperial court set up twelve prisons, namely, the ceremonial prison, the internal official prison, the royal prison, the royal horse prison (hereinafter referred to as the superior prison), the secretary prison, the superior security prison, the golden valley prison, the superior justice prison, the direct code prison and the superior prison. In fact, they are all institutions that serve the emperor and the royal family. The service content is interesting, you can tell at a glance. The internal affairs office of the Qing Dynasty also had this function. The main function of the Ministry of Internal Affairs is to manage royal affairs, such as royal daily meals, clothing, storage, etiquette, engineering, farms, animal husbandry, guards' retinue, mining and fishing in Yamazawa, etc. , but also to control the salt policy, collect tariffs and accept tributes.