Dating Systems and Calendars

The concept of a single date can be complex and interpreted differently across various systems.
Examples of diverse dating systems mentioned:
- Jewish Calendar: For August $12$ , $2012$ C.E., it was $26 Ab 5772$ .
- Islamic Calendar: For August $12$ , $2012$ C.E., it was $24 Ramadan 1433$ A.H. (after Hijra).
- Roman Calendar: For August $12$ , $2012$ C.E., it was pridie Idus Augustas, $2765$ A.U.C. (from the founding of the city).
- Mayan Calendar: An example date shown as $12 - 19 - 19 - 11 - 9$ .

Global Prominence and Influence:
- It is the most commonly used calendar worldwide.
- This widespread adoption is primarily due to European/Western global influence over the past $5$ centuries.
Origins:
- Its roots trace back to the Ancient Egyptian solar calendar.
- Further modified by the Roman dictator Julius Caesar, leading to the Julian calendar.
- Subsequently adopted and reoriented by the Roman Catholic Church, eventually becoming the Gregorian calendar.
Dividing History: A.D. and B.C.
- The Church reoriented this calendar to divide history into two main eras.
- These eras are fundamentally separated by the calculated birth of Jesus Christ.
- The Roman Catholic Church designated the year of Jesus' birth as A.D. $1$ .
  - A.D. stands for "Anno Domini," which is Latin for "in the year of the Lord."
- The year immediately preceding Jesus' birth was designated as $1$ B.C.
  - B.C. stands for "Before Christ."
- Crucial Point: There is no year " $0$ " in this dating system.
Understanding Date Progression:
- Moving Towards the Present (A.D. / C.E.): Dates of years grow numerically larger as one moves closer to the present. For example, A.D. $1875$ was more recent than A.D. $720$ .
- Moving Backward in Time (B.C. / B.C.E.): Dates of years also grow numerically larger as one goes further back in time before the year $1$ B.C. For example, $1543$ B.C. was further back in time than $44$ B.C. (which was the year Julius Caesar was assassinated).

Terminology for Academic Use: For the course, dates will be expressed using B.C.E. and C.E. instead of B.C. and A.D.
B.C.E. (Before the Common Era):
- This suffix refers to the same years as those designated by B.C.
- Example: $200$ B.C. is equivalent to $200$ B.C.E.
C.E. (Common Era):
- This prefix refers to the same years as those designated by A.D.
- Example: $2023$ A.D. is equivalent to $2023$ C.E.
Consistency: The actual dates and the dividing line between eras (the calculated birth of Jesus) remain exactly the same; only the terminology has changed.

Definition: Centuries are periods of $100$ years, used to categorize time within this dating system.
Numbering Convention (C.E.):
- Dates falling between $1$ and $100$ C.E. are described as taking place in the $1^{st}$ century C.E.
- Dates falling between $301$ and $400$ C.E. are described as taking place in the $4^{th}$ century C.E.
- Current Example: We live in the year $2022$ C.E., which falls within the $21^{st}$ century C.E.
Reason for Discrepancy (Year vs. Century Number):
- There is no "century $0$ " in the dating system.
- Counting begins with $1$ for the first $100$ years (i.e., years $1 - 100$ C.E. constitute the $1^{st}$ century).
Backward in Time (B.C.E.): The same numbering principle applies to B.C.E. dates.
- $1546$ B.C.E. was in the $16^{th}$ century B.C.E. (since it falls between $1501$ and $1600$ B.C.E. when counting backwards).
- $255$ B.C.E. was in the $3^{rd}$ century B.C.E. (since it falls between $201$ and $300$ B.C.E. when counting backwards).

Definition: Millennia represent periods of $1000$ years.
Current Millennium: We are currently in the $3^{rd}$ millennium C.E.
- Its dates span from $2001$ C.E. to $3000$ C.E.
Historical Example: Civilization is considered to have begun in the $4^{th}$ millennium B.C.E.
- This period falls between $3001$ and $4000$ B.C.E.