Calendars and Dating Systems

While our dating system may seem obvious, it is not universal, and can even be considered controversial. There are many different dating systems still in use today, and even more that were previously used, which can confuse the matter of assigning dates to events.

See "List of Calendars" on Wikipedia to see just how many different dating systems exist.

Major Calendars Currently in UseGregorian - this is the one generally used in western

society today, and the we are familiar with, having 12 months and 365 fully days, with periodic leap days/years. The year zero is set as the year Christians traditionally consider to be the year Jesus was born. Years prior to this are counted backwards, and after to this are counted forwards.

Julian – this is almost the same as the Gregorian calendar, but it determines leap days differently. Because of this, it is currently 13 days behind the Gregorian date. It was used throughout Europe, but countries gradually switched to Gregorian; it is still used by the Eastern Orthodox church for calculating holy days

The switch from Julian to Gregorian dating started in 1582, but happened very gradually (Greece didn’t make the switch until 1923)

When looking at primary sources, be aware that the date might be using a different calendar

Islamic Calendar – Also called Hijri calendar, noted as AHA lunar calendar with 12 months and 354 daysIt is used to date events in many Muslim

countries, and to calculate dates for important dates, such as Ramadan when to go attend Hajj (the Gregorian calendar is used for most other things)

The year zero is calculated from the year Mohammad emigrated to Medina, which was 622 CE in the Gregorian Calendar

Current year is 1435 AH

Other Calendars Some governments will create calendars to

promote a political ideologyJuche era calendar – North Korea

Many religions have their own calendars, as well

Some cultures use traditional calendar systems, or will use traditional ones for specific functions, such as calculating lucky days for weddings, feasts, etc.

In this course, events will generally be referred to using the Gregorian calendar; secondary and tertiary sources will have converted the dates from any other system to our own

The one thing that will be inconsistent is how the year is referenced

Year NotationTraditionally, years prior to zero were given

the notation BC (Before Christ), while dates after zero were noted as AD (Anno Domini, or In the Year of The Lord)

This is considered problematic, and has changed

To reduce the inherent cultural bias in the calendar, and make it more inclusive, the current convention is to use BCE (Before Common Era) for pre-zero years and CE (Common Era) for post-zero years. Depending on the source material you use in your research, you will likely see both notations used. Your textbook, because it is old, still uses BC/AD, while a current textbook would likely use BCE/CE.

**In your writing, please use BCE/CE, as this is the current standard for historical work.**

Other Year Notationskya – thousand years ago

Generally used for the Neolithic and earlier50 000 years ago would be 50 kya

MA (or, rarely, mya) – million years agoSometimes use decimals – 780 000 years ago

would be 0.78 mya

BP – Before PresentGenerally assumes to use 1950 as “present”