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Summary
The abbreviations BCE and CE are nonreligious alternatives to BC and AD. While the BCE/CE notation is generally preferred in scientific and academic writing, BC/AD is the more common choice in writing meant for a general audience.
Examples
- Egypt was under Roman rule from 30 BC to AD 641.
- Egypt was under Roman rule from 30 BCE to 641 CE.
or
Periods, which may or may not be used, are generally omitted in formal writing. Don’t enclose the abbreviations in commas. Also note that while BC, BCE, and CE are placed after the date, AD generally appears before.
Example
- 200 BC but AD 200.
The abbreviation AD isn’t written unless necessary: if the era isn’t specified, it is assumed to be AD.
Example
- The telescope was first patented in
AD1608.Understood to be AD and not BC.
Eras
An era is a system of dates based on a particular event. The most commonly used Western system of chronology is the Christian Era, which dates from the birth of Jesus Christ and uses the abbreviations BC and AD. Another popular convention is the Common Era, which is numerically the same but denotes the era using BCE and CE.
Examples
- The British Iron Age lasted from 800 BC to AD 100.
- Hunter-gatherer societies in North America were building monumental mound complexes as early as 3000 BC.
- Seals dated to 2600 BCE have been found in the basins of the Indus River.
In this article, we discuss various systems used to specify time periods, along with rules and guidelines on how to use them correctly.
BC and AD
The abbreviations BC (before Christ) and AD (anno Domini, or in the year of the Lord) are used to label years and centuries.
Examples
- The Roman era began in the eighth century BC.
- Alexander the Great died in 323 BC.
- Rome was the capital of the Roman empire from 27 BC to AD 286.
There is no year zero: the year that follows 1 BC is AD 1, with the birth of Jesus Christ as point zero on this date line.
Caution
Note that BC always goes after the date: 223 BC, or 223 years before Christ. By convention, AD appears before the date: AD 223, or in the year (of the Lord) 223. Don’t enclose the abbreviations in commas.
Example
- This is a story about the rise and fall of an empire over 500 years: from 300 BC to AD 200.
With names of centuries, both abbreviations appear after.
Example
- The Roman Empire lasted from the first century BC to the fifth century AD.
Periods are unnecessary but not incorrect in abbreviations with all capital letters. Style guides differ in their recommendations: the Chicago Manual of Style suggests omitting the periods; the AP Stylebook recommends using them.
Examples
- Chicago: For having ideas of his own, Socrates was sentenced to death in 399 BC.
- AP: For having ideas of his own, Socrates was sentenced to death in 399 B.C.
or
In formal writing, periods are generally omitted.
Examples
By 6000 BC even the marshes had largely gone, drowned by the sea.
— “Neolithic and Bronze Ages,” BBC History (2014)
The civilization that arose on the mainland under Cretan influence in the 16th century BC is called Mycenaean after Mycenae.
— “Aegean Civilizations,” Encyclopaedia Britannica (1999)
Chandler’s book includes population data from 2250 BC to AD 1975 in various charts and tables.
— “Spatializing 6,000 years of global urbanization from 3700 BC to AD 2000,” Nature (June 7, 2016)
Also, these abbreviations have traditionally been printed in small capital letters: BC and AD. This style is less common now, especially in digital media. The Chicago Manual of Style, for example, no longer recommends small caps.
Tip
When the era is unspecified, it is assumed to be AD. Use AD only when not using it would result in confusion.
Examples
- The Byzantine empire fell to the Ottomans in
AD1453.Understood to be AD rather than BC, without needing to be specified.
- China was ruled by the Han dynasty from 202 BC to AD 220.
Without BC and AD being specified, these dates would be confusing.
but
BCE and CE
The abbreviations BCE (before Common Era) and CE (Common Era) are the secular alternatives to BC and AD. This notation system for dates has been in use for centuries and is now the preferred choice in much of scientific and academic writing.
Examples
- Five Sumerian poems dating from 2100 BCE are our first introduction to the Gilgamesh Epic.
the same date as 2100 BC
- The first complex Mayan societies existed from 2000 BCE to 250 CE.
the same time period as 2000 BC to AD 250
Tip
Writing CE is generally unnecessary. If nothing is specified, the year is presumed to be CE.
Examples
- Jane Austen was born in 1775
CE. - The Mughal empire lasted from the fourteenth to the eighteenth century
CE. - The Yayoi period in Japan lasted from 300 BCE to 300 CE.
Specify both BCE and CE when necessary.
but
BC and AD vs. BCE and CE
The two systems—BC and AD, and BCE and CE—are numerically equivalent and indicate exactly the same dates. The BCE/CE notation system is simply the religiously neutral alternative to BC/AD. In scholarly literature, BCE and CE are now often preferred. For example, the Encyclopaedia Britannica now prefers BCE and CE, as do many academic and scientific journals.
Examples
When it was finally conquered by the Romans in 64 BCE, the formerly mighty Seleucid empire was confined to the provinces of Syria and eastern Cilicia, and even those were under tenuous control.
— “Seleucid Empire,” Encyclopaedia Britannica (1998)
Diabetes, from 1500 BCE to 2000 CE
— Title of an article in The Lancet, published 2014
In writing aimed at a more general audience, BC and AD are still commonly used, presumably because readers are more familiar with these abbreviations. The AP Stylebook for instance recommends the use of BC and AD (but with periods: B.C. and A.D.).
Examples
The decline of Bronze-Age civilizations in Egypt, Greece and Mesopotamia has been attributed to a long-term drought that began around 2000 BC.
— “200-Year Drought Doomed Indus Valley Civilization,” Scientific American, (2014)
She lived on an island in the Baltic Sea around 3,700 B.C.
— “DNA from Stone Age ‘Chewing Gum’ Tells an Incredible Story,” National Geographic (2019)
Tip
Consider your audience when deciding which era system to use: BC and AD or BCE and CE. Some may prefer BCE/CE for being religiously neutral, while others may be more familiar with BC/AD.
Time scale in archaeology: BP
The abbreviation BP (before the present) placed after a number denotes the number of years before the present time. Since the present year changes each year, archaeologists, geologists, and other scientists consider AD 1950 to be “the present.” So 2000 BP is 2000 years before 1950—i.e., 50 BC.
Examples
Although few archaeological data have been recovered from the period from roughly 12,000 to 9000 BP in China, the presence of settlements in Japan at that time suggests that further investigations will reveal analogous developments on the continent.
— “Origins of Agriculture,” Encyclopaedia Britannica (1999)
The present volume is the culmination (and publication) of a rather ambitious project involving changing understandings of the human body from the Upper Paleolithic (ca. 40,000 BP) down to contemporary times.
— “The Body in History: Europe from the Palaeolithic to the Future,” American Journal of Archaeology (2015)
The valley sites were dated to around 2000 BP, whereas the one site excavated outside the valley on the Divide, near the headwaters of the Goulburn, appeared to date from about 7750 BP.
— “Results of an archaeological survey of the Hunter River Valley, New South Wales, Australia,” The Australian Museum (1981)
