The Tibetan calendar, a kind of almanac created by Tibetans has a history of 1300 years. The Tibetan calendar is mixed with the calendar of Yin and Yang, which is divided one year into four seasons: winter, spring, summer and autumn. The first month of the twelve is Yin (correspondent to March). The big months alternate with the small months. After every two or three years an intercalary month is added to regulate the seasons. It is quite different between the intercalary time and agricultural calendar. Due to being influenced by the Han calendar, the heavenly stems have always designed the Tibetan calendar and Earthly branches as annuals. Its difference is used the Five Elements to go instead of ten Heavenly stems. Jia yi (the first and the second of the ten heavenly stems) is symbolized of wood. Bing din (the third and the fourth) is symbolized of fire. Mao ji (the fifth and the sixth) is symbolized of earth. Geng xin (the seventh and the eighth) is symbolized of gold. Ren kui (the ninth and the tenth) is symbolized of water. Any of the twelve animals goes instead of the twelve Earthly branches such as Zhi is symbolized of the rat. Chou is symbolized of oxen and so on. For instance, Jia zhi year in lunar calendar is called the year of fire tiger in Tibetan calendar. A cycle of sixty years is called Rabchungin Tibetan calendar, which is similar in content to the sixty year-old in the hinterland of China.