Why are the supreme rulers of slave society, such as Dayu, Tang Cheng and Zhou Wuwang, called "kings" instead of emperors?

"Emperor" belongs to the religious category. The original meaning is God, heaven.

The son of heaven is the son of heaven who rules the world. Sacrifice after death should be accompanied by heaven, so it is called "emperor" after death. In the past, three emperors and five emperors were honorifics after death.

After the Warring States period, religious consciousness was weak, and the concept of emperor was rarely used.

After Qin Shihuang destroyed the Six Kingdoms, he thought that his achievements were better than those of the Three Emperors and Five Emperors, so he asked his ministers to call themselves "emperors". From then on, the son of heaven was also called the "emperor" when he was alive.

The king is a political category. Three horizontal lines represent heaven and earth. One vertical represents unity.

"Shuo Wen Jie Zi" said: Wang, go. "Wang" relies on morality and excellent ruling style. Everyone in the world wants to be ruled by "Wang", so they all move closer to the place of "Wang".

Therefore, "Wang" is the highest ruler in the world.

In the Western Zhou Dynasty, the king was the son of heaven and the supreme ruler of the world. Later, after Qin Shihuang called him "the emperor", the king was reduced to the next level of ruler and was no longer the son of heaven.

China people believe that there is only one son of heaven. So, at the same time, there is only one real son of heaven, and that is the emperor. Other kings are not sons of heaven, so there can be many.

Since the Han Dynasty, only the emperor's relatives can be made king to consolidate the emperor's rule. The monarch of China's dependent country can also be king to show the unity of the world. Like the king of Korea.

When China is divided, several emperors will not recognize each other. Because "there are no two days, and people have no two masters." During the Three Kingdoms period, three emperors. Ha ha.

During the Five Dynasties, the whole country was divided into several countries, and Vietnam was one of them. But most of these countries were later unified in the Song Dynasty. But Vietnam is too far away to be unified, so Vietnam is independent. Vietnam thinks that they and Song Dynasty are both China, Song Dynasty is the Northern Dynasty, and Vietnam is the Southern Dynasty. Vietnamese rulers also call themselves emperors. Similar to the mainland and Taiwan Province province now.

Among East Asian countries, only Japan has never been occupied by China. So Japanese rulers can secretly call themselves the emperor. But the ruler of Japan has no real power, so he is called the "Emperor".