Origin

In the antient times, Chinese people use the System of Ten Celestial Stems and Twelve Branches to represent years, which is sixty years for a cycle. But, it is quite difficulte for people to remember the names of those Ten Celestial Stems and Twelve Branches. Therefore people use different animals to represent the Twelve Branches. It is simple and interesting. What is more, it is easy to remember.

The corresponding relationship between the Twelve Animals and the Twelve Branches initially emerged more than 2500 years ago. But the complete version of Zodiac is found in the documents of the Dong Han Dynasty. The version is almost the same as today's. The Zodiac was associated with the years people borne and became the signs of people.

Then why just use twelve animals, not eleven and not thirteen? It is based on astronomy. Ancestors found the cycle of winter and summer, and found that a cycle includes twelve times of full moon. They deemed the number twelve as a mysterious number to show the thought of the God. So, we now have twelve animals to represent years.