Dating Systems Notes

Dating Systems: Study Notes

  • This set of slides introduces how humans designate years and dates using different calendars, and how historians refer to time across eras. It also highlights the Western (Gregorian) calendar as the most common today and explains the origins and terminology around BC/AD and BCE/CE, including the absence of a year 0. The material uses several calendar systems as examples.

Overview: What is a dating system?

  • Dating systems assign a numerical label to points in time (years, centuries, millennia).

  • The date a document or post was released can itself be a point of study in how calendars label time (example shown: "August 12, 2012" and the hint "Or was it?").

Calendar examples from different cultures (page 2)

  • Jewish calendar example: 26extAb577226 ext{ Ab }5772 (26 Ab = month 26 in the Hebrew year 5772)

  • Islamic calendar example: 24extRamadan1433extA.H.24 ext{ Ramadan }1433 ext{ A.H.} (A.H. = After Hijra)

  • Roman calendar example: extpridieIdusAugustas,2765extA.U.C.ext{pridie Idus Augustas}, 2765 ext{ A.U.C.} (A.U.C. = Ab urbe condita, from the founding of Rome; pridie Idus Augustas = the day before the Ides of August)

  • Mayan calendar example: 12ext–19ext–19ext–11ext–912 ext{–}19 ext{–}19 ext{–}11 ext{–}9 (a Mayan long-count style date)

  • Takeaway: There are multiple dating systems in use historically and culturally, each with its own epoch, units, and notation.

The Western (Gregorian) calendar: prevalence and origin (page 3)

  • The most commonly used calendar in the world today is the Western (Gregorian) calendar.

  • Why is it so widespread? Because of European/Western global influence over the past five centuries.

  • Its origins trace back to an ancient Egyptian solar calendar and were modified by Julius Caesar, leading to the Julian calendar (which the Gregorian calendar refined).

The role of the Church in dating (page 4)

  • Adoption by the Roman Catholic Church.

  • The Church reoriented historical time into two eras based on the birth of Jesus Christ.

  • The year system was calculated to place Jesus’ birth at the start of a new era: A.D. 1 marks the first year of this era.

  • A.D. stands for "Anno Domini" in Latin, meaning "in the year of the Lord".

  • The year before Jesus’ birth was designated 1 B.C. (Before Christ).

BC/AD and BCE/CE terminology (pages 4–7)

  • B.C. means "Before Christ".

  • There is no year "0" in the BC/AD system.

  • AD is now commonly referred to as CE (Common Era); BC is referred to as BCE (Before Common Era).

  • For this course, dates will be presented as:

    • B.C.E. — "Before the Common Era" (equivalent years to B.C.)

    • C.E. — "Common Era" (equivalent years to A.D.)

  • Importantly, the BCE/CE dividing line is the same as the BC/AD dividing line; the numerical labels do not change, only the labels do.

  • Summary mapping:

    • B.C.E. year X corresponds to the same numeric year as B.C.

    • C.E. year X corresponds to the same numeric year as A.D.

Centuries and the dating system (page 8)

  • Centuries and millennia can be described using the CE/BCE framework.

  • Example: Years 1–100 C.E. are described as the 1st century C.E.

  • Example: Years 301–400 C.E. are described as the 4th century C.E.

  • Practical note: The century numbering reflects the order in which years flow, not a separate counting of centuries.

Why there is no year 0 and how centuries are counted (page 9)

  • We currently live in the 21st century (example given: the year 2022 is in the 21st century).

  • There is no century "0"; counting begins at 1 for the first century (years 1–100 C.E.).

  • The same rule applies when looking backward in time:

    • 1546 B.C.E. falls in the 16th century B.C.E.

    • 255 B.C.E. falls in the 3rd century B.C.E.

  • Core takeaway: Century counting starts at 1, not 0.

Millennia and the far larger time scales (page 10)

  • Millennia denote spans of 1,000 years.

  • We are in the 3rd millennium C.E. (years 20012001 to 30003000 C.E.).

    • Notation: 2001ext−−3000extC.E.2001 ext{--}3000 ext{ C.E.}

  • Civilizations began in the 4th millennium B.C.E. (years 4000extB.C.E.extto3001extB.C.E.4000 ext{ B.C.E.} ext{ to } 3001 ext{ B.C.E.}).

    • Notation: 3001ext−−4000extB.C.E.3001 ext{--}4000 ext{ B.C.E.} (spanning from 4000 B.C.E. down to 3001 B.C.E.).

  • Quick recap of scales:

    • Century ≈ 100 years

    • Millennium ≈ 1,000 years

  • Brief self-check (to be attempted after studying the material):

Self-check prompts (page 11) and suggested answers

  • Question 1: What century was 243 B.C.E. in?

    • Answer: 3rd century B.C.E. (years 300 B.C.E. down to 201 B.C.E.)

  • Question 2: What century was 543 C.E. in?

    • Answer: 6th century C.E. (years 501 C.E. to 600 C.E.)

  • Question 3: What millennium was 1643 B.C.E. in?

    • Answer: 2nd millennium B.C.E. (spanning 2000 B.C.E. down to 1001 B.C.E.)

  • Question 4: What millennium was 1211 B.C.E. in?

    • Answer: 2nd millennium B.C.E. (spanning 2000 B.C.E. down to 1001 B.C.E.)

Key terms and concepts (glossary)

  • Anno Domini (A.D.) — Latin for "in the year of the Lord"; indicates years counted since the birth of Christ.

  • Before Christ (B.C.) — the years before the traditionally calculated birth of Christ.

  • Before the Common Era (B.C.E.) — alternative labeling for BC years; same numerical years as BC.

  • Common Era (C.E.) — alternative labeling for AD years; same numerical years as AD.

  • Ab urbe condita (A.U.C.) — Latin for "from the founding of the city" (Rome); used in Roman dating.

  • Pridie Idus Augustas — Latin phrase meaning "the day before the Ides of August"; a Roman dating indicator.

  • Ides of August — August 13 (historical reference in the Roman calendar).

  • Jewish calendar — Lunar-solar calendar with year counts like 5772 in the Hebrew calendar.

  • Islamic calendar — Lunar calendar with year counts like 1433 A.H. (A.H. = After Hijra).

  • Mayan calendar — A diverse set of dating systems within the Mayan civilization; example date notation shown as a long-count sequence.

  • Century — 100-year block (e.g., 1st century C.E. covers years 1–100 C.E.).

  • Millennium — 1,000-year block (e.g., 3rd millennium C.E. covers years 2001–3000 C.E.).

Remarks on real-world relevance and implications

  • The choice of calendar system affects how history is recorded, taught, and understood, and reflects cultural influence (e.g., European colonial expansion contributing to the ubiquity of the Gregorian calendar).

  • BCE/CE is often used to shift away from specific religious labeling (BC/AD) while preserving the same year numbers; this has ethical and pluralistic implications in modern scholarship.

  • The absence of a year 0 affects mathematical calculations across BC/AD or BCE/CE transitions, requiring careful handling in date arithmetic.

  • When teaching or learning history, it is important to recognize that different cultures (Jewish, Islamic, Roman, Mayan) used distinct calendars with different year-counting bases, epochs, and era divisions.

Quick reference conversions (examples)

  • Century boundaries:

    • The 1st century C.E.: 1extto100extC.E.1 ext{ to } 100 ext{ C.E.}

    • The 4th century C.E.: 301extto400extC.E.301 ext{ to } 400 ext{ C.E.}

  • BCE/CE relationship without a year 0:

    • If given a BCE year y, its astronomical year is −(y−1)-(y-1) when converting to a zero-based system.

    • There is no year 0 in the BC/AD framework; the sequence goes 1 B.C. → A.D. 1.

  • Millennium example:

    • 3rd millennium C.E.: 2001extto3000extC.E.2001 ext{ to } 3000 ext{ C.E.}

    • 4th millennium B.C.E.: 4000extB.C.E.extdownto3001extB.C.E.4000 ext{ B.C.E.} ext{ down to } 3001 ext{ B.C.E.}

If you would like, I can tailor these notes to a specific course format (e.g., more emphasis on BCE/CE terminology, or more worked date-conversion examples).