The history of using 12-year animal cycles to record the years in China dates back to 100 A.D. Each year is represented by an animal and the 12 animals are mouse, ox, tiger, rabbit, dragon, snake, horse, goat, monkey,rooster,dog and pig.

As to the order of these 12 animals, there is a legend. Every one among the 12 wants to be placed first of the cycle. Hence, a fairy proposes a contest: the order will be decided by the places in the competition that reaching the opposite bank of the river. Unknown to the ox, the rat jumps upon his back at the very beginning. As the ox is about to go ashore, rat jumps off his back and wins the race. As to the pig, he becomes the last one for his laziness.