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.

Example - how to date the silver bar: a combination of the cyclic date 丁酉 and the reign title 明命 gives the year 1837.