As there was no identifying star at the centre of the Black Tortoise, the appropriate place (the eleventh mansion) was called Void.” In the same book, Walters explains: “However, it seems that before the adoption of the Four Celestial Emblems, there were only three -- the Feng Bird (or Phoenix), the Dragon, and the Ch’i-lin (or unicorn).
Bronze mirrors usually portray cosmological patterns and symbolism on the back.
Those of the Tang period (618 - 906 AD) show all twelve, or sometimes the 28 or even 36 animals of the Chinese Zodiac, and those of an earlier period depict the four celestial emblems referred to above.
But the very earliest mirrors show only the three: the Ch’i-lin, the Feng-huang, and the Dragon.
Because of the astronomical significance, the White Tiger replaced the Ch’i-lin, and the Phoenix gave way to the Red Bird, which is of uncertain identity.
Dragon; Ryū (Ryu) 龍 or Seiryū (Seiryu) 青龍 in Japan, Qinglong in China.Associated closely with China’s Five Element Theory.At the heart of Chinese mythology are four spiritual creatures (Sì Shòu 四獸) -- four celestial emblems -- each guarding a direction on the compass.Further, each corresponds to a quadrant in the sky, with each quadrant containing seven seishuku, or star constellations (also called the 28 lunar mansions or lodges; for charts, see this outside site).Each of the four groups of seven is associated with one of the four celestial creatures.