How Did Ancient People Use Calendars?

Oldest Calendars

The oldest ‘calendars‘ are vast archaeological sites that aligned posts or megaliths (giant stones) with the rising of the Sun or Moon on significant dates, such as the summer or winter solsticeThe earliest structures built as calendars seem to be designed to help calculate the solar and lunar months. Priest-astronomers used these. 

Prehistoric astronomers left no user manuals for their monuments – their uses had to be rediscovered by archaeoastronomersarchaeologists with knowledge of astronomy. 

Warren Field, Scotland, found in 2004, is the earliest site found so far. It tracks events some 10,000 years ago.

Development of Accurate Calendars

Calendar development was often driven by the need to fix religious festivals and observance, an impulse that continued with the formation of new religions such as Christianity and Islam. Both put astronomy to use in this way.

Arab astronomers and engineers were zealous in their pursuit of improved methods for keeping time so that daily prayers could be received by the devout at the right time.

Time-keeping on a larger scale was essential in scheduling religious festivals.

Lunar Calendars 

Time is naturally divided astronomically by the Earth’s orbit around the Sun (a year), the Earth’s rotation (a day) and the phases of the Moon. A lunar month (a full cycle from one new or full moon to the next is approximately 29 1/2 days. A year is 365 1/4 days.

Inconveniently, a year is 12.37 lunar months long. For early societies, a lunar month was a useful and countable period of time, one that could be easily observed and checked just by looking up at the night sky.

But if you use 12  lunar months as the basis of your year, the calendar will drift out of sync quite quickly. It will be a month out after only 3 years, and 6 months out after 18 years. To avoid this, an extra (intercalary) month has to be added every few years.

Egyptian Calendars

The ancient Egyptians began their year with the rising of Sirius (which they called Sopdet) above the horizon before sun rise.

  • System dates to c. 3000 BC.
  • Divided year into 365 days.
  • Used two different calendars.
  • Sirius, a stable star, and the brightest star in the night sky, was the basis for the Egyptian calendar.
  • Ptolemaic rulers depended on calendars.

Other cultures developed independent calendars, notably China and Mesoamerican (Central American) civilizations.

Chinese Yin-Yang Li Traditional Calendar

Origins of the Chinese calendar can be traced back to 14th century BC, though legend says it was invented in 2637 BC.

  • Literally ‘heaven-Earth’ calendar.
  • Used alongside imported calendars such as the Hindu calendar.
  • Used until 1912, when China officially adopted the Western Gregorian calendar.

How the World Works: Astronomy: From Plotting the Stars to Pulsars and Black Holes
How the World Works: Astronomy: From Plotting the Stars to Pulsars and Black Holes 

Anne Rooney

Background on Anne Rooney

Why is Easter Celebrated on Different Calendar Dates From Year To Year?


Standardization of Easter Celebration Date

The Catholic Church fixes the date of Easter, its celebration to mark the resurrection of Christ, using a method set out in AD 325 by the Council of Nicaea. In the first centuries AD, Easter was celebrated on different days by different groups of Christians, the Council of Nicaea sought to standardize it.

Role of Full Moon

Easter is now celebrated on the first Sunday after the full moon occurring on or after the spring equinox. Early Christians couldn’t simply wait to find out when the full moon would fall, then quickly celebrate Easter. They had to fit in Lent – 40 days of fasting – immediately beforehand, so had to know several weeks in advance when that full moon would fall, a task that could only be achieved by keeping astronomical records and projecting into the future.

Easter Dates 

How the World Works: Astronomy: From Plotting the Stars to Pulsars and Black Holes
How the World Works: Astronomy: From Plotting the Stars to Pulsars and Black Holes
Anne Rooney

Background on Anne Rooney

Persian Road System – The World’s Original Information Superhighway

Persian Empire Royal Road System

The ultimate basis of the Persian Empire’s greatness was not its bureaucracy, nor even its armies, but its roads the world’s original information superhighway. It’s no wonder control of such a service by Darius, the Great King, should have overawed his subjects, and struck them as the surest gauge and manifestation of Persian power.

Persia’s road system, known as the Royal Road, provided the immensity of the empire’s body with its nervous system, along which news was perpetually flowing, from synapse to synapse, to and from the brain. 

The distances were routinely annihilated by royal couriers. Every evening, after a hard day’s ride, the messenger would find a posting station waiting for him, equipped with a bed, provisions and a fresh horse for the morning.

A truly urgent message, one brought at a gallop through storms and the dead of night, might arrive in Persepolis from the Aegean in under two weeks. This was an incredible, almost magical, degree of speed. Nothing to equal it had ever been known before.

Persian Road System

Access to the Road System

Access to the road system was ferociously restricted. No one could set foot on it without a pass, a viyataka.  Mere possession of such a pass was a mark of prestige. So tightly controlled were the itineraries of travelers on the roads that those who dawdled on the way and failed to arrive at a given destination on an alloted date could expect to forfeit their rations for the night.

Those who traveled on the roads without a viyataka pass would not merely go hungry, but very quickly be hunted down and killed. Even mail if it were sent without royal approval would be destroyed. Only the most cunning could hope to evade the vigilance of the highway patrols.

Immensity of the Persian Empire

The first dynasty of the Persian Empire was created by Achaemenids, established by Cyrus the Great in 550 BCE with the conquest of the MedianLydian and Babylonian empires. It covered much of the Ancient world and controlled the largest percentage of the earth’s population in history when it was conquered by Alexander the Great.

Persian Empire
………………The Persian Empire

Darius, the Great King, ruled the Persian Empire at its peak, from 552-486 BCE (36 years), when it included a vast area, including: much of West Asia, the Caucasus, parts of the Balkans (ThraceMacedonia and Paeonia), most of the Black Sea coastal regions, parts of the North CaucasusCentral Asia, as far as the Indus Valley in the far east, and portions of north and northeast Africa including Egypt (Mudrâya), eastern Libya and coastal Sudan.

Persian Fire: The First World Empire and the Battle for the West
Persian Fire: The First World Empire and the Battle for the West
Tom Holland



Tom Holland
Tom Holland

born 1968

. Tom Holland website
. Wikipedia

Tom Holland is a British writer and popular historian. He has published several non-academic works on classical and medieval history. In addition to his writing work, he has worked with BBC, adapting Homer, Herodotus, Thucydides and Virgil for TV documentaries also focusing on history.

Holland lives in London with his wife and two daughters. He is a keen cricket fan and member of the Authors XI cricket team.

Books Tom Holland has written include:


Frankincense and Myrrh – Ancient Treasure


Incense Kingdoms of Southern Arabia

The incense kingdoms of Southern Arabia (today’s Yemen and Oman) produced the finest quality frankincense and myrrh – two of the most sought-after commodities of the ancient world. They also had a virtual monopoly on the transport and distribution of these two valuable items.

In the comparative peace brought by the Roman Emperor Augustus, at the end of the first century BC, demand for frankincense and myrrh was soaring. Thousands of pounds of incense were making their way by land and sea to Alexandria, Rome and Gaza, to the former Persian Empire now controlled by Parthians, to India and even China.

Frankincense and Myrrh

Frankincense – Good as Gold

Frankincense, the resin from the Boswellia tree, was as expensive as gold at the time of Jesus. Frankincense was the ancient world’s equivalent of crude oil. It was an indispensable element of public and private life, of all religious and state ceremonies in the Roman Empire as in the rest of the then known world.

Frankincense was probably the most essential luxury of the ancient world, and it made the kingdoms of Southern Arabia fabulously wealthy.

Myrrh – More Expensive Than Frankincense

Myrrh, a thorny bush, which like frankincense grew in Southern Arabia, was the essential ingredient for embalming bodies. More expensive than frankincense, it was in less demand and used less frequently in religious ceremonies.

Like frankincense, myrrh was mixed in cosmetics and perfumes and was used as a cure-all, including to prevent poisoning. It was also used to relieve pain, which may have been why Jesus was offered a mixture of myrrh and wine before the crucifixion.

More About Frankincense…

Ingredient in Worship by Various Traditions

  • Temple of the Greek sun-god Apollo.
  • Roman God of war Mars.
  • Babylonian sun-god Bel.
  • Temple in Jerusalem.
  • Buddhist temples in India.
  • Italian peasant farmer shrines.

Variety of Uses

  • Used to fend off the stench of ordinary living if you could afford it.
  • In oils for massages at the baths.
  • In face packs for pampered women.
  • To perfume Cleopatra’s barge when she sailed from Egypt to Tarsus for her first encounter with Mark Antony.
  • Mixed in the mortar of houses.
  • Was the aspirin of its day, used as a cure for anything from depression to dysentery.
  • In eye makeup.

And Man Created God
And Man Created God: A History of the World at the Time of Jesus

Selina O’Grady



Selina O'Grady
Selina O’Grady

. Selina O’Grady (website)

Selina O’Grady is a writer, producer, and speaker.

O’Grady is the co-editor of two books: Great Spirits: The Fifty-Two Christians who Most Influenced their Millennium and A Deep But Dazzling Darkness. She has reviewed regularly for the San Francisco Chronicle, Literary Review and Tablet.

O’Grady was a producer of BBC1’s moral documentary series Heart of the Matter presented by Joan Bakewell, Channel 4’s live chat show After Dark, and Radio 4’s history series Leviathan.


What Does the History of Morality Tell Us About Humanity?

What can the history of morality tell us about the nature of morality? And, what can it tell us about ourselves as human beings?

Morality is like a map guiding us from the way humans are to the way we think humans ought to be. It is, however, a most unusual kind of map. Most maps help you locate the starting point of the journey and the destination, and pinpoint the route that can take you from one to the other. Not so in the case of morality. On the moral map the starting point, the destination, and the route are all created during the journey itself.

The story of morality is the story of how the relationship between these two visions of the human – the relationship between how we might imagine humans are and how we envision they can be – has changed over time and across space, from Homer’s Greece to Mao’s China, from ancient India to modern America.

Our understanding of what it is to be human, of human nature, has changed over time. Additionally, what it is to be human only makes sense in light of our conception of the kind of beings we want to be, and the kind of world we want to live in.

To look upon morality as a historical product is not to degrade it, but, rather to breathe life into it – to understand morality as a human creation, to recognize it not as a fixed monument but as an evolving story. History becomes a tool through which to discover that values have changed, and why, and what it tells us about our moral lives today.

When we look upon morality as a historical product, it allows us to ask questions such as these:

  • Why were ancient Greek gods so immoral?
  • How did China manage, for more than two millennia, to create a strong ethical framework without the need for God?
  • Why did caste became so important in India?
  • Why did Augustine, one of the greatest Christian theologians, think slavery and torture were morally acceptable?
  • Why was the Europe of the Enlightenment (18th century) also the Europe of imperial terror?
  • How are contemporary claims that science can define moral norms an echo of the religious idea that values derive from God?

A historical account might undermine the idea of moral injunctions as absolute and objective, but it also reveals new ways to think of moral norms as more than merely a matter of personal preference or political need.

The Quest For Moral A Compass: A Global History of Ethics
The Quest for a Moral Compass: A Global History of Ethics
Kenan Malik




Kenan Malik
Kenan Malik
born 1960

. Kenan Malik (website)
. Pandemonium (website)
. Wikipedia

Kenan Malik is an Indian-born British writer, lecturer and broadcaster, trained in neurobiology and the history of science. As a scientific author, his focus is on the philosophy of biology, and contemporary theories of multiculturalismpluralism and race.

Malik has given lectures or seminars at a number of universities, including: Cambridge; Oxford; Institute of Historical Research, London; University of Oslo; and the European University Institute, Florence. In 2003, he was a visiting fellow at the University of Melbourne. He is currently Senior Visiting Fellow at the University of Surrey.

Malik has been a presenter and panelist on the BBC radio programs Analysis, Night Waves, and Moral Waves. He has written and presented a number of TV documentaries, including Disunited Kingdom (2003), Are Muslims Hated? (which was shortlisted for the Index on Censorship Freedom of Expression award, in 2005), Let ‘Em All In (2005) and Britain’s Tribal Tensions (2006). ‘Strange Fruit’ was longlisted for the Royal Society Science Book Prize in 2009.

Books written by Kenan Malik include: