Coligny Calendar: The 1,800-Year-Old Lunisolar calendar banned by the Romans

Coligny Calendar:  The 1,800-Year-Old Lunisolar calendar banned by the Romans

In 1897, the Gaulish Coligny Calendar was discovered in Coligny, Ain, France.  The bronze calendar was found broken into 73 pieces, which together form a 5 foot wide, 3.5 foot high bronze tablet. When assembled, it displays a lunisolar calendar, which follows both moon phases and the time of solar year. It is believed that the calendar, dating back to the 2nd century AD, had been banned by the Romans as it indicated druidic practices. The calendar can now be found at the Gallo-Roman Museum of Lyon.

Map of France showing location of Coligny

Map of France showing location of Coligny (Wikipedia)

The age of the calendar has been estimated based upon the styling of the letters and images it contains. French archaeologist, J. Monard, has speculated that the druids created the calendar as a means of preserving the druid tradition of timekeeping at a time when the Julian calendar was being heavily promoted throughout the Roman Empire.  Druid were members of the educated, professional class among the Celtic peoples of Gaul, Britain, Ireland, and possibly elsewhere during the Iron Age. The druid class included law-speakers, poets and doctors, among other learned professions, although the best known among the druids were the religious leaders.

An Arch Druid in His Judicial Habit

Imaginative illustration of ‘An Arch Druid in His Judicial Habit’, from “The Costume of the Original Inhabitants of the British Islands” by S.R. Meyrick and C.H. Smith (1815), the gold gorget collar copying Irish Bronze Age examples. (Wikimedia Commons)

A calendar similar to the Coligny calendar was found nearby at Villards d’Heria.  Both calendars follow the Contintental Celtic calendar. Through reconstruction, researchers have been able to determine that the calendar is a lunisolar calendar, focusing on the lunar month and the solar year. Scholars have disagreed as to whether a new month began with the new moon, full moon, or the first quarter moon.  The lunar year was made up of 354 or 355 days. There is dispute as to whether the calendar began in summer or autumn. The starting month, Samonios, is generally affiliated with Old Irish Samhain on October 31. However, Samon is Gaulish for summer.

Like the modern calendar, the Coligny calendar is comprised of 12 months, with each month containing 29-30 days. The months include:

Month Time Period Meaning Days
Samonios October – November Seed-fall 30
Dumannios November – December The Darkest Depths 29
Riuros December – January Cold-time 30
Anagantios January – February Stay-home-time 29
Ogronios February – March Time of Ice 30
Cutios March – April Time of Winds 30
Giamonios April – May Shoots-show 29
Simivisionios May – June Time of Brightness 30
Equos June – July Horse-time 29/30
Elembiuos July – August Claim-time 29
Edrinios August – September Arbitration-time 30
Cantios September – October Song-time 20
Sonnocingos  Intercalary “Sun’s march” 30

To follow the solar year, the 13th intercalary month, referred to as Sonnocingos, was included every 2.5 years. The intercalary month alternated between being inserted before Samonios and being inserted in between Cutios and Giamonios. Each month into the calendar was divided into halves, with the second half serving as an atenoux or “renewal.” The two halves were also known as the “light” half and the “dark” half, following the new moon, and indicating that it had some religious significance.  Overall, the calendar followed thirty-year periods, split into smaller five-month segments. Each five-month segment contained 62 months, including the intercalary months. According to some researchers, this cycling creates an error in following the moon cycles.

Segment from the Coligny calendar

Segment from the Coligny calendar (

The Coligny calendar provides insight into how some viewed the world, moon cycles, and sun cycles during ancient times. At the time when it was created, the Julian calendar was being imposed throughout the Roman Empire. The discovery of the Coligny Calendar shows how others viewed and measured the passage of time, days, months, and years. Although calendaring has changed over time, it is clear that one thing has not changed – the use of moon phases and the Earth’s revolution around the sun to measure the passage of time.

Featured image: Image source:


Coligny Calendar – Wikipedia. Available from:

The Coligny Tablet – Roman Britain. Available from:

The Gaulish (Coligny) Calendar – Time Meddler. Available from:

By M R Reese

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