In Chinese culture, the tiger is the king of the beasts and has been presented with a 王 on his forehead for centuries. According to legend, the tiger's tail would turn into white when it reached the age of 500 years. In this way, the white tiger became a kind of mythological creature. It was said that the white tiger would only appear when the emperor ruled with absolute virtue, or if there was peace throughout the world. Because the color white of the Wu Xing theory also represents the west, the white tiger became a mythological guardian of the west.