In the Chinese calendar, each year is represented by an animal of the zodiac. There are 12 animals and therefore 12-year cycles. Here we find a fundamental notion: contrary to Westerners for whom time is linear, the Chinese consider that time is cyclical. Thus, according to the law of Yin and Yang, every event repeats itself. This is the basis of the I Ching, considered to be the oldest book of divination still in use.
A legend says that just before entering nirvana, Buddha called for the animals. Only 12 animals responded to his call. To reward them, Buddha assigned each of them a year in the order of their arrival. The rat arrived first and was honoured with the first year. Then came the ox, followed by the tiger, the hare, the dragon, the snake, the horse, the goat, the monkey, the rooster, the dog, and the pig.
Another legend tells of a race organised by the Jade Emperor to cross a river. The rat got on the back of the ox (and took advantage of it to push the cat into the water, which is not part of the dream team) and finished first, before the ox, because it jumped on the shore. The pig came last because of a digestive nap.
Whatever the legend, we have the twelve animals that make up the Chinese zodiac. None of the twelve animals represents a star or constellation. Rather, the animals represent the movement of the Chi of the earth expressed in periods. This is also called the Earth Branches, the same ones that are used for a bazi analysis.