In ancient times, there was basically an unwritten rule that craftsmen who built imperial tombs, especially those who built underground palaces, had to die. In fact, the reason itself is very simple, that is, to prevent the entrance of the underground palace from leaking out and make the emperor restless after a hundred years, so these craftsmen who built the imperial tomb have to die. However, these are often the meaning of the next emperor. The first emperor was buried after his death, and he needed to be buried after the funeral. During this period, when the new emperor ascended the throne and buried the first emperor, after the coffin of the first emperor was finally put in, when the underground palace was closed, these craftsmen would be ordered to be executed in advance or suffocated in the underground palace.