Alright, let’s ease everybody into this whole thing with a quick look at how the Chinese zodiac came to be… …at least according to the legends. Trying to find out how the ancient peoples of China came to chose such an astrological system is impossible. Unless someone out there has a time machine they are willing to loan.
The story begins with the Jade Emperor realizing that, despite being the literal ruler of heaven and earth, he knows very little about the fauna of half of his domain. So he sent out a proclamation to all animals of the earth to come to him so he could learn more about them. But wait! There’s more! The first twelve animals to arrive get the eternal honor of being in the zodiac!
The Cat and the Rat are excited about all this until they realized that getting to this grand audience would require crossing a great river. And both Cat and Rat are terrible swimmers. Luckily, Ox is really nice and will happily let both of them ride on his back as he crosses the river. About halfway through, though, Cat get’s knocked off Ox’s back by the devious Rat, and when the riverbank is close, Rat jumps off Ox to win first place in the Jade Emperor’s competition, with the Ox in second.
Third place went to Tiger after a long swim against strong currents. Rabbit came in fourth by nimbly hopping from stone to stone, nearly falling in the water at one point, but managing to hop onto a log that was blown to shore.
Then came the mighty, flying Dragon. Confused as to why a flying creature was only in fifth, the Jade Emperor learned that Dragon had been busy making rain for the people and animals of the earth when the summons came and had provided the breath of wind that allowed Rabbit to make it to shore.
Horse and Snake were next, but Horse reared back when it realized Snake had been coiled around it’s hoof. Thus Snake was sixth and Horse was seventh. Animals eight, nine, and ten were Goat, Monkey, and Rooster, who had noticed a raft on the river and worked together to get it across.
Dog was eleventh in the race because squirrel, while the hungry Pig, who ate a big meal and napped on the way, finally came in as the Jade Emporer was about to call it quits. The Cat drowned thanks to Rat’s treachery. And that’s why cats eat rats.
Buddhist sources will usually have the Buddha issuing the summons rather than the Jade Emporer. Other places within the Chinese sphere of influence will have a similar calendar but replace and animal. For example, the Rabbit in Vietnam’s zodiac is replaced by the Cat.