The major problem with the events in ancient Indian History is not so much as their historicity but as their chronology. That is the reason that the dates of the Mahabharata war, the date of Nirvana of the Buddha or of Mahavira or even of Sankara are still matters of debate, study and research.
Although the ancient Indians were great calculators of time, they, somehow, did not standardize the dates of important events in a uniform manner. That might have been because the ancient India, except for the two relatively brief imperial periods of the Mauryas and the Guptas, 321 BCE to 185 BCE and 320 AD to 467 AD , for rest of the period was largely politically and culturally fragmented into regional segments. There were also numerous ancient Indian calendars, each with its own commencement year, which were used by different dynasties or religious communities or regions.
The chronology, which we now refer to, was put in place during the later years of the 18th century (around the year 1793) largely due to the efforts of Sir William Jones. It was built around two factors: One, the date of the death of the Alexander the Great; and two, the identification of Sandrocottus mentioned in the Greek accounts with Chandragupta Maurya. Of the two, the former, that is, the date of the death of Alexander the Great is verifiable from other sources. However, it is the identity of Sandrocottus with Chandragupta Maurya that is still a matter of debate. Thus the chronology of Indian History, as we now follow, is supported on one leg by a fact and on the other by an assumption.
This was, broadly, how the chronology was worked out.
The first fixed point in this chronology was the year 326 BCE, when according to the Greek writers Plutarch and Justin a young Indian prince Sandrocottus met Alexander then camping at Taxila. After the death of Alexander in 323 BCE, his empire broke up and Sandrocottus of Palibothra established himself and ruled over a large region.
Now, the Indian scholars of 18th century identified Sandrocottus with Chandragupta Maurya and Palibothra with Pataliputra (in the region of present day Patna), because of the phonetic similarities.
That was how the death of Alexander and equating Sandrocottus with Chandragupta Maurya became the sheet anchor of the ancient Indian chronology.
The working of the dates of the Buddha, Asoka and others was attempted along the following lines.
1. Alexander the Great died in the year 323 BCE (taken as an undisputed date).
2. Sandrocottus equated with Chandra Gupta Maurya began his reign in the year of Alexander’s death (323 BC).
3. According to the list of Kings given in the Puranas, Chandragupta Maurya ruled for 24 years, so did his successor Bindusara (323 -24-24 =275 BCE)
4. Asoka came to the throne some years after the death of his father Bindusara because of the succession wars (275 -6 = 269 BCE), Asoka ruled for 36 years (269-36 = 233 BCE).
5. According to the Sinhalese chronicles, Asoka’s coronation took place 218 years after the death of the Buddha. Therefore, the Buddha’s Nirvana might have taken place in the year 487 BCE (269 + 218).
6. The Buddha lived for about 80 years. He therefore might have been born around 567 BCE. His date might therefore be between 487 BCE and 567 BCE.
Another method was also employed. The king Bimbisara (Vidhisara) was a contemporary of the Buddha. Bimbisara sent his personal physician Jivaka to attend on the Buddha. His son Ajathashatru of the Sisunaga dynasty of Magadha succeeded Bimbisara. When Ajathashatru came to the throne, the Buddha was 72 years of age. The Buddha died 8 years later. All generally accept these events.
According to these events and with reference to the Puranic records the time of Bimbisara is reckoned as 580 – 552 BCE and that of Ajathashatru as 552 – 527 BCE.
Since the Buddha died 8 years after Ajathashatru came to throne, the year of the Buddha’s death is taken as 544 BCE. And, the life of the Buddha is therefore taken as between 644 and 544 BCE.
The dates of the Buddha’s birth and death are still uncertain .The most commonly used dates are between 644 BCE to 544 BCE. Yet, all dates within 20 years of either side are also acceptable.
In any case, the Buddha’s period is in the sixth century BCE.
Identifying Sandrocottus with Chandragupta Maurya, though looks rather convenient, has given rise to a number of unanswered questions. It sometimes looks as though Sandracottus might not have been Chandragupta Maurya afterall.
1. According to the Greek accounts, Sandrokottus deposed Xandrammes and Sandrocyptus was the son of Sandrokottus. In the case of Chandragupta Maurya, he had opposed Dhanananda of the Nanda dynasty and the name of his son was Bindusara. Both these names, Dhanananda and Bindusara, have no phonetic similarity with the names Xandrammes and Sandrocyptus of the Greek accounts.
1. a. Some scholars surmise that Sandracuttos mentioned by the Greek writers might actually refer to Chandragupta of the Gupta dynasty. The kings before and after Chandragupta Gupta were Chandramas and Samudragupta. The phonetic similarity is quite apparent for Chandragupta Gupta and not Maurya.
Chandragupta of Guptas is now placed in fourth century AD. In case he is indentified with Sandracottos, then the entire chronology will shift back by about eight hundred years .Then the Buddha might as well have been in the 14th century BCE.
2. The Greek accounts cover the period from 4th century BC to 2nd century AD. None of them has mentioned the names of Kautilya or Asoka. It was with Kautilya’s assistance that Chandragupta had come to the throne. Asoka’s empire was bigger than that of Chandragupta and he had sent missionaries to the Yavana countries. However, both of them are not mentioned. The Greek writers did not say anything about the Buddhist Bhikkus though that was the flourishing religion of that time with the royal patronage of Asoka. The Indian scholars wonder why the Greek accounts are silent on Asoka and Buddhism.
The ancestry of Chandragupta is still shrouded in mystery and not known for certain. There are divergent views regarding the origin, and each view has its own set of adherents. Please check the following site for further discussions on the issue. Please also visit Talk: Ancestry of Chandragupta Maurya
Please check the following for the other side of the issue:
The another reference point that is often relied upon is the work of the famous astronomer Aryabhatta who wrote his definitive mathematical work in 499 AD. Aryabhatta through his astronomical calculations, claimed that the year of completion of his work (499 AD) also marked 3,600 years of the Kali Yuga. It , indirectly, meant, that Kali Yuga commenced in or around 3101 BC.
The other method was calculating the dates from the start-year of the Islamic lunar calendar (622 AD). According to that reckoning, Mahmud of Ghazni attacked India in 1000 AD.
But again, the modern European system of dating is not entirely accurate either. That is because, Christ was born at least four years before what we consider to be its start-year of 1 AD , supposedly the year of his birth. Apart from that , there have also been both slippages of days and days added artificially by the Church at different times in European history.
Nevertheless, the present dating system is commonly accepted; and, is compared with many Indian calendars. Of course, one needs to be constantly reminded that all dates of ancient Indian history are somewhat fluid; and, in the dating of some events one has to accommodate a certain ‘give and take’ of a few decades or even a couple of centuries , at times .
Talking of chronology in Indian History, Shri Niraj Mohanka (not a professional historian) has produced a remarkable set of spreadsheets – 23 columns wide, 350 rows deep and over 8,000 cells in MS Excel – basically on the chronology of Indian history. The like of which I had not come across. As the chronology in Indian History is always a matter of debate, one may quarrel a bit with the dates indicated by Shri Mohanka, this way or that. But that does not, in any manner, take away the sheen from the dedication and the amount of scholarship and work that has gone into producing the document.
Please check : http://www.newdharma.org/royal_chron.htm
In the webpage, the following link opens up a Microsoft Excel file that contains four spreadsheets (see the four lower Tabs when you open up the Excel file):
1) Royal Chronology of India (Columns K through P on the right-hand side describe other civilizations – Egypt, Israel, Iraq, Iran and China). On Page 21 of this file is a Population Chart of India from 8000 B.C.E. to 2200 C.E. On Page 42 is a list of assumptions and sources used to build the timeline.
2) The History of World Religion- major religions [Eastern AND Western] have roots in the Vedas
3) Comparison of All Religions
4) Festivals of India
In the webpage please click on the above picture