The si ling, also called the ssu ling, are the Chinese spiritual animals. These creatures have been used for centuries to represent the four cardinal directions, and are a deeply-rooted aspect of Chinese mythology.
According to Chinese mythology, the mythological empress Nu Wa became a goddess when she ascended to the celestial regions. After much chaos throughout the kindom, she created the four spiritual beings and placed each as guardian over one quadrant of the sky.
The following creatures protected the four cardinal points, and each point's respective quadrant: the feng-huang, or phoenix, to the South; the gui xian, or tortoise, to the North; the long, or dragon, to the East; and the qilin, or unicorn, to the West. Instead of the qilin representing the West, the byakko, or tiger, is used in some cases; however, the qilin is most commonly used. Also, the Chinese people used the fifth cardinal point, the center, which was synonomous with China.
The Chinese believe there are 28 seishuku, or constellations, seven in each quadrant; therefore, each si ling corresponds to the seven seishuku in it's quadrant. In the northern quadrant, protected by gui xian, there were the seishuku hatsui-boshi, hikitsu-boshi, inami-boshi, namae-boshi, tomite-boshi, umiyame-boshi, and uruki-boshi. In the feng-huang's region, the southern quadrant,
were the seishuku chichiri-boshi, chiriko-boshi, hotohori-boshi, mitsukakae-boshi, nuriko-boshi, tamahome-boshi, and tasuki-boshi. To the eastern quadrant, guarded by long, were ami-boshi, ashitare-boshi, mi-boshi, nakago-boshi, soi-boshi, su-boshi, and tomo-boshi. And in the western quadrant, protected by the qilin or byakko, the seishuku amerufi-boshi, ekie-boshi, kagasuki-boshi, subaru-boshi, tatara-boshi, tokaki-boshi, and toroki-boshi reside.
The si ling, while not still considered to be the gods they once were, still hold an important place in Chinese culture. Dances are performed and festivals celebrated in their honor, and they still hold great symbolism for the Chinese people.
For more in-depth information on each of the spiritual beings, check out these nodes: