The name of the Forbidden City comes from the metaphor of Ziwei Garden. Ancient astronomers in China once divided the stars in the sky into three constellations, twenty-eight constellations and other constellations. The three walls include Taiwei Garden, Ziwei Garden and Tianshi Garden. Ziweiyuan is in the middle of the three yuan. According to the ancient astronomy in China and the long-term observation of space objects, the Ziwei Academy is considered as the residence of the Emperor of Heaven, and its eternal position is in the center of the sky. Therefore, the heavenly palace where the Emperor of Heaven lives is the Purple Palace. "Forbidden" is easier to understand, which means that the palace is a royal place, and others are not allowed to come here.

The feudal emperor claimed to be the son of the heavenly emperor and thought he was the real dragon emperor. And the palace where they live is compared to the purple palace in the sky. They prefer to live in the Purple Palace, rule the country by virtue, naturalize in all directions, and come to Korea from all directions to achieve the goal of maintaining long-term rule.