What do you mean, how to explain it and how to understand it?

This is a question of ancient sacrificial rites and patriarchal clan system. The Zhou dynasty stipulated that the emperor could set up seven ancestors of the temple, with the ancestral hall in the middle. Zhou people regarded Hou Ji as the ancestor, and the ancestor did not participate in Zhao Mu's arrangement. The following ancestors were ranked by Zuo Zhao and You Mu, and the Zhou Dynasty was really established when Wu Wang Jifa was born, but his father Moon Hee Chang was the founder of the foundation of the Zhou Dynasty, with three points in the world.