BCE, CE, BC and AD
Most history writing in English counts years from a traditional date for the birth of Jesus. Years before it are written BCE (before the common era) or BC (before Christ). Years after it are CE (common era) or AD (anno Domini, "in the year of the Lord"). The numbers are identical in both systems. Many academic writers prefer BCE and CE because they are neutral about religion, and that is the style used on this site.
Two quirks catch students out:
- There is no year zero. The year 1 BCE is followed directly by 1 CE. To find the span between a BCE date and a CE date, add the numbers and subtract one.
- BCE years count down. 500 BCE is earlier than 400 BCE. Augustus became the first Roman emperor in 27 BCE, so he ruled after Julius Caesar, who was killed in 44 BCE.
The system of counting years from the birth of Jesus was worked out in the 500s CE and spread slowly in Europe over the following centuries. Other calendars, such as the Islamic, Hebrew and Chinese calendars, count years differently and are still used today.
How centuries are named
A century takes the number one higher than the hundreds in its years. The 1700s are the eighteenth century. The 1900s are the twentieth century. The same rule works backwards: the fifth century BCE runs from 500 to 401 BCE, the age of classical Athens.
| Years | Century | Example |
|---|---|---|
| 500 to 401 BCE | 5th century BCE | Athenian democracy and the Persian Wars |
| 1 to 100 CE | 1st century CE | The early Roman Empire |
| 1001 to 1100 | 11th century | The Norman conquest of England, 1066 |
| 1701 to 1800 | 18th century | The American and French Revolutions |
| 1901 to 2000 | 20th century | Both world wars |
Strictly, a century starts in a year ending in 01. In everyday writing, "the eighteenth century" and "the 1700s" are used for the same span, and nobody will mark you down for that.
Circa, ranges and uncertain dates
When a date is an estimate, historians put "c." (circa) in front of it. Early dates often rest on archaeology, astronomical records, lists of rulers or texts written much later, so scholars give a best estimate and revise it when new evidence arrives. Dates for Egyptian dynasties, for example, vary by decades between reference works. When you write an essay, use the dates from your course textbook and be consistent.
Julian and Gregorian calendars
Julius Caesar introduced the Julian calendar in 46 BCE. Its year ran slightly too long, and by the 1500s it had drifted about ten days from the seasons. In 1582 Pope Gregory XIII introduced the corrected Gregorian calendar, which Catholic countries adopted first. Others followed much later:
- Britain and its American colonies switched in 1752. In that year, September 2 was followed by September 14.
- Russia switched in 1918, after the Bolshevik seizure of power. That is why the October Revolution of 1917 fell in November by the Gregorian calendar.
When two sources give different dates for the same event, check which calendar each one used before you assume one is wrong.
Periodization: who decides when an era starts?
Labels such as "medieval," "early modern" and "the Enlightenment" were invented after the fact, mostly by European writers. They are tools for organizing the past, and historians argue about them. When did the Middle Ages end: with the fall of Constantinople in 1453, Columbus's first voyage in 1492, or the start of the Reformation in 1517? Each answer puts the emphasis on a different kind of change.
Periods also travel badly. A "medieval" label fits Europe better than China or West Africa, where different turning points matter. World history courses such as AP World History use broad date bands for this reason, and they describe processes that cross regions, such as trade, migration and the spread of religions.
If an exam question asks you to judge a turning point, it is asking you to argue about periodization. Explain what changed, what stayed the same, and why your chosen date matters more than another.
Dates and periods FAQ
Should I write BCE or BC?
Either is correct if you use it consistently. Follow your teacher's or publisher's style. BCE and CE are common in academic history and on exams.
What does "fl." mean next to a name?
It stands for floruit, Latin for "flourished." Historians use it when they know when someone was active but not when they were born or died.
Is the "Dark Ages" still an accepted term?
Most historians avoid it. The early medieval period left fewer written sources in parts of western Europe, but archaeology and other records show active trade, learning and state-building. The term also says little about the rest of the world.