Vietnamese Cyclic Chronology
Eastern calendar is based on two cycles:
- the cycle of ten Heavenly Stems, associated with Yin/Yang and Five Elements, and
- the cycle of twelve Earthly Branches, associated with twelve animals of Asian Zodiac.
Together, these cycles form a 60-year stem-branch cycle. Two cyclic characters in combination with two (sometimes more) characters of the Reign Title indicate the exact date.