King was originally the title for the “Son of Heaven,” namely, the country’s supreme ruler in the Xia, Shang and Zhou dynasties. From the Spring and Autumn Period onward, the power of the Zhou court gradually weakened and the kingdom disintegrated. By the time of the Warring States Period, any monarch could call himself a king. Up to the Qin and Han dynasties, king became the highest title granted by the emperor to a male member of the imperial family. In the political philosophical discourse of Confucianism, especially in the works of Confucius and Mencius, a king represents heaven’s will and therefore ought to have supreme, unchallengeable power; at the same time, he is imbued with a high moral attribute and political ideals. According to Confucianism, to be a king is to unify or govern the country with benevolence and righteousness, or to win over people by morally justified means. Likewise, the pursuit of the kingly way means using benevolent and righteous means to unify and govern the country.
He to whom the people swear allegiance can rule as a king; he perishes when the people desert him. (Xunzi)