The Tomb Feng Shui tells that a descendant will become an emperor, if a tomb is built at a place, named Zhen Long Di (the place of real dragons), where especially good qi (positive energy) is concentrated. It is said that Mao Zedong is a case in point: he got the power because the tomb of his grandfather was situated at Zhen Long Di. This paper analyses eleven kinds of legend of Zhen Long Di, which have been ignored in the folklore studies, and compares them with the famous legend of Gan Sheng Di (an emperor who is born, corresponding to Heaven). In the legend of Zhen Long Di, people have the decisive role in making an emperor or enjoying power and fortune by finding a good graveyard and holding services for his ancestors: the good qi from the land is said to correspond to the descendants through a tomb or bones of their ancestors. I will conceptualize this crucial role of people by the term of Ren Zu Ganying (correspondence between people and ancestors) and contrast it to Tian Ren Ganying (correspondence between Heaven and people) in the legend of Gan Sheng Di, where Heaven plays the main role. Then this paper will argue existence of a belief in revolutionary power-changes by Ren Zu Ganying at very root both of the obsession of people to the Feng Shui of tombs and of the spread of this legend over a wide area.