Seasons from the Sun
Kamal Lodaya, Bengaluru

This is a series about calendar makers from history.

The earlier articles talked about {lunar} calendars based on {phases} of the Moon, {seasonal} calendars based on seasonal happenings (such as rains or river flooding which were important for farmers) and {intercalary} calendars whose years were seasonal but whose months were based on the Moon's phases. Today we know that the rotation of Earth {precesses}, like a top whose axis keeps shifting slightly as it spins. This makes the solstices (longest and shortest days) shift to an earlier date every year, which becomes noticeable over centuries. To fix this, a {leap day} was introduced to the seasonal year every four years.

There are several calendars in India, using different Eras. The earlier calendars were based on the Moon.


Piyadasi Era, 3rd century BCE
{Samvat} is a Sanskrit word meaning year. Jains are an Indian religious community who use {samvatsari} (literally, a date which comes yearly) for the end of the fasts of {paryushana} (literally, coming together), a day on which they seek forgiveness from others. It is a fact that in Indian history, Jains were active in using calendars. The Maurya ruler Ashoka (3rd century BCE) allowed may religions to flourish. Merchants took loans and used {adesha} ("bills" promising repayment) in the empire. It is suspected that Jain calendars were in use. The famous rock edicts of Piyadasi (a name used by Ashoka) use his own Era. That is, they say that the edict was inscribed so many years since Piyadasi became emperor.


Shaka Era, from 2nd century CE
The Shaka empire (also called Kshatrapa, {kshetrapati} meaning ruler of the land) was in northwestern and central India. The Shakas traded with Greeks from the port of Bharuch in Gujarat. They used the Greek calendar of Meton (4th century BCE) and Hipparcos (3rd century BCE), which had reached India by the 1st century CE. It may have replaced the Jain calendar. The Greeks talked of Barygaza (Bharuch) and Ozene, which we recognize as Ujjain, Madhya Pradesh. Ujjain has been an important city for Indian calendar makers because it lies almost on the Tropic of Cancer. The Sun is overhead here on summer solstice, noon of June 21st.

The {Shalivahana Shaka Era} begins in 78 CE with the year the Shaka ruler Chashtana (Tiastanes in Greek) started ruling in Ujjain, defeating the Satavahanas who ruled Maharashtra and Andhra Pradesh. Both kingdoms fought many battles over Ujjain. Chashtana's kingdom included Malwa, Gujarat and Sindh. An inscription written in year 11 of his rule (89 CE) has been found in Kachchh. There are many different dates for the Shaka Era. A century after Chashtana, another ruler chose to accept Chashtana's rule as the beginning of the Era instead of starting a new one. Shaka Era was widely used from the 5th to the 7th centuries. It also spread to Indian kingdoms in Southeast Asia.


Gupta Era, from 4th century CE
The Guptas used their own Era, starting from 319 CE. In the 5th century CE, emperor Samudragupta named his grandfather Chandragupta II as {Vikramaditya} (literally "sun of valour"), which became popular as a title among kings. In the Gupta period, Jains moved from Bihar to settle in central and western India.


Kali Yuga, from 6th century CE
The Tamils followed a completely different seasonal calendar, based on the Sun, the months being related to the seasons by the Sangam poet Nakkirar around the 3rd century CE. The year began on 14th April with the month of Chittirai. The North Indian seasonal calendar's month of Chaitra begins on 22nd March. See the table below.

Why is the Tamil calendar ahead by three weeks?
The spring equinox was on 14th April in the year 285 CE. Then the Sun was exactly opposite the Chittirai (Chitra) nakshatra (star).

The Tamil seasonal calendar is used in Tamilnadu, Kerala, Assam, Bengal, Manipur, Odisha, Punjab, Rajasthan and Nepal. 25th August 2021 is {Kaliyuga} year 5123, Aavani month, 9th day. You can calculate from this that Kaliyuga started from a date in 3102 BCE.

This dating of Kaliyuga was done in year 3600 (499 CE) by Aryabhata, an Ashmaka (most likely from the Godavari valley) who lived in Kusumapura (Nalanda or Patna, in Bihar). A century later, he was criticized by Brahmagupta of Bhinmal (Jalore district, Rajasthan) for starting his own Era. Brahmagupta used the Shaka Era. At that time Bhinmal was ruled by Gurjara kings from Gujarat. It was a place of Jain pilgrimage and has been known for its moneylenders for centuries.


Vikram Samvat, from 8th century CE
By the 5th century CE, the Jains were using Vir Samvat, which counts years since the death of Mahavira, traditionally dated to 527 BCE. Centuries later (the earliest inscription in Okha, Gujarat, mentions Vikram Samvat 794), this was recalibrated as {Vikram Samvat}, after a legendary ruler called Vikram from Pratishthana (Paithan, Maharashtra). Paithan is known as a place of Hindu, Jain and Buddhist pilgrimage. Vikram is said to have defeated the Shakas and ruled Ujjain from 57 BCE (Vir Samvat 470) for about a decade before the Shakas came back to power. The date matches with an inscription in Naneghat cave, Maharashtra, mentioning Satavahana ruler Satakarni I.

Rivalry between Shakas and Satavahanas led to two different Eras in Indian calendars. As can be seen their history is quite mixed up. The name {Shalivahana Shaka} respects both traditions.

The intercalary Samvat calendar is used in North India, Gujarat, Maharashtra, Karnataka and Andhra. 25th August 2021 is 2078 Vikram Samvat, Bhadra month, krishna paksha, 3rd day. For Jains the new year begins with the month of Kartika, so 25th August 2021 is in year 2077 of the Vikram Samvat. 


Summary
We mainly use three Eras today in India: Kaliyuga, starting in 3102 BCE; Vikrama, starting in 57 BCE (Kaliyuga 3045), and Shalivahana Shaka, starting in 78 CE (Kaliyuga 3179, Vikrama 134).

Some of the Indian calendars are: the Hindu and the Jain intercalary calendars, in North India (Shaka and Vikrama Eras); the National seasonal calendar, in North India (Shalivahana Shaka Era); the Tamil seasonal calendar, in the South (Kaliyuga Era). There are more. Every calendar borrows several things from others.

The table shows the beginning dates of months this year for these three Eras. Observe how the Vikram Samvat months are at first ahead of the National calendar months, but they keep lagging behind. At the end of the year they are behind the National months. In another year they will be falling really behind and it will be time to introduce an extra month ({adhika maasa}) to correct the calendar. Who is to decide this? We will find out in the next issue of {JM}.


Table: 3 calendars for 2021-22 CE

National year 1943, Vikram Samvat year 2077-78, Tamil year 5123

Chaitra Mar22, Chaitra Mar29, Chittirai Apr14
Vaishakha Apr21, Vaishakha Apr27, Vaigasi May14
Jyeshtha May22, Jyeshtha May27, Aani June15
Ashadha June22, Ashadha June25, Aadi July16
Shravana July23, Shravana July24, Aavani Aug17
Bhadra Aug23, Bhadra Aug23, Purattasi Sep17
Ashwina Sep23, Ashwina Sep21, Aippasi Oct17
Kartika Oct23, Kartika Oct21, Karthigai Nov16
Agrahayana Nov22, Mrigashira Nov20, Margazhi Dec16
Pausha Dec22, Pausha Dec20, Thai Jan14
Magha Jan21, Magha Jan18, Masi Feb13
Phalguna Feb20, Phalguna Feb17, Panguni Mar14
Chaitra Mar22, Chaitra Mar19, Chittirai Apr14

The beginning of Vikram Samvat 2078 differs in different parts of India.
For the Jains, it begins on 5th November 2021, the day after Kartika amavasya (Deepavali).


Box: Years and numbers, BCE and CE
There were many calendars in BCE, Before the Common Era, which was introduced after the life of Jesus Christ. If you know your school mathematics, you might say the Roman emperor Julius Caesar was born in the year -100 (100 BCE) and died in the year -44 (44 BCE). Here is a trick question about Eras, which might puzzle you. Since Jesus Christ was not even born, how did the calendars of those times know what was zero? Think about it.

So you leapt ahead to think about how people thought about zero before zero was invented? No, they didn't think about zero. The day after December 31 of 1 BCE (first year before the Common Era) is January 1 of 1 CE (first year of the Common Era). There is no zero year.

Zero the number is a little different from the zeroes that appear inside numbers, such as 100 or 101 or 120. People wrote these earlier like we speak them today, as one hundred (write it as 1H) or as one hundred and one (1H1U) or as one hundred and twenty (1H2T). People knew how to count from very long ago.

END OF BOX

Box: Numbers and zero, 2nd to 5th century CE
Thinking about zero as a number comes from India. Shunya (emptiness) is discussed at great length by the Buddhist philosopher Nagarjuna, who lived in Amaravati (Vijayawada) in the 2nd century CE where the Satavahana kings ruled. From his texts, it cannot be said whether he was familiar with zero as a number.

The earliest confirmed dated text where we realize that the writer knew zero is by Digambar Jain monk Sarvanandi in Patalika (Tiruppadirippuliyur, Cuddalore district, Tamil Nadu).

The date on which his text was completed is given as Shaka year 380, Bhadra month, krishna paksha, 15th day. Using today's calendar this date is 25th August 458 CE. 25th August 2021 is 1943 Shaka, Bhadra month, 3rd day. So 458 CE being 380 Shaka checks out. The month agrees but the date doesn't. There is a gap of 12 days. Remember that intercalary and seasonal calendars can differ in their dates by upto one month.

Sarvanandi also says it was the 22nd year of king Simhavarman of Kanchipuram, which matches a Pallava king called Simhavarman II. Some years before this, Sarvanandi says he attended the Jain council at Valabhi, near Bhavnagar in Saurashtra, Gujarat, where he was instructed to prepare the book he wrote. A council was held there in 453 CE.

Sarvanandi's text {Lokavibhaga} describes the Jain universe. So you leapt to ask why is it thought that the writer was comfortable with zero? It uses huge numbers like 14236713, 13107200000, 70500000000000000, which show that the writer knew the decimal system very well. It uses the fact that (14230249-355684)/212 is 65446 with 13/212 left over, so the writer knew arithmetic. It uses the word {shunya} for an "empty" answer. The writer must have been as familiar with decimal arithmetic as an ace schoolchild today. So we can be confident that zero the number was known in the 5th century CE.

END OF BOX