Timing of Mahabharata war is (was) being connected with the beginning of Kali-yuga with the assistance of not only few factual but also many assumed statements.
Let’s explore this journey in the language of mathematics.
Let ‘X’ be the year of Mahabharata war
Mahabharata text states that Krishna passed away 36 years after the Mahabharata war.
Thus, Year of Krishna’s passing away = X +36
Although we don’t know exactly who did it and how they did it, The beginning of Kaliyuga was fixed by Indian astronomers at 3102 BCE.
While Puranic records do not clearly refer to any specific evidence, that by itself, would allow us to reach 3102 BCE as the beginning of Kaliyuga, it appears that Puranic records seem to align with this assumption for the beginning of Kaliyuga (3102 BCE)
Calendars exists from as early as 7th century CE that assume 3102 BCE as the beginning of Kaliyuga for their computations.
I have been told that available epigraphic evidence also follows 3102 BCE as the beginning of Kaliyuga.
Thus, while the origination and the rationale for the date remains unknown and uncertain, the assumption of 3102 BCE = Beginning of Kaliyuga appears to be fixed/established during the writings of Purana literature (especially Bhagavad Purana, Vishnu Purana, but also other puranas) and also during the time of Vriddha Garga, Varahamihir and Aryabhatta.
Assumed beginning of Kaliyuga = 3102 BCE
Mahabharata text has few astronomy observations (e.g. AV observation or set of observation of Bhishma Nirvana) that would falsify any year of Mahabharata war that would fall after 4500 BCE.
In fact, I have corroborated year of 5561 BCE (originally proposed by Dr. P V Vartak) as the year of Mahabharata war, with astronomy, chronology and seasonal evidence (more than 200 specific references) of the Mahabharata text.
Mahabharata text does not have any astronomy, chronology or other such evidence that would allow one to arrive at 3102 BCE as the beginning of Kaliyuga.
Against this background, it is also true…
As Shri Vedveer Arya writes…
“The epoch of Kaliyuga is very old and all Indian literary and epigraphic evidence leads to the epoch of 3102 BC and Puranas were written considering MB around 3138 BCE.”
And hence the question…
How the year of Mahabharata war (X) got linked with 3102 BCE?
Here is the answer.
The Purana writers also assumed the following.
(I am quoting longer passage from this chapter because it has references that are employed by numerous Purana researchers in estimating the year of Mahabharata war by combining it with what they know (or think they know) of the timing of Mahapadma Nanada.)
The critical verse for our current discussion is Bhagavad Purana 12:2:33
Bhagavad Purana, Skandha 12, Adhyaya 2
(26) Beginning from the birth of your good self up until the coronation of king Nanda [see 12.1: 12] eleven hundred and fifty years will pass [*].
(27-28) When the constellation of the seven sages (Ursa Major, the Great Bear) rises are the first two of them (Pulaha and Kratu) seen in the sky, in between them on the same line [northwest] in the night sky is their [ruling] lunar mansion seen. The sages [the stars] connected remain with that lunar mansion for a hundred human years. Now, in your time, are the twice-born situated in the nakshatra called Maghâ.
(29) With Vishnu, the Supreme Lord, the sun known as Krishna having returned to heaven, this world has entered the age of Kali in which people delight in sin.
(30) As long as He, the Husband of Ramâ, touched the earth with His lotus feet, Kali couldn’t really take possession of her.
(31) When the [constellation of the] seven sages among the gods enter[s] Maghâ, Kali-yuga begins. That period covers twelve hundred years
(32) When the seven sages pass from Maghâ to the lunar mansion of Pûrvâsâdhâ, will from the time of [Mahâpadma] Nanda and his descendants on, this age of Kali gain its full strength.
(33) The historians say that the day that S’rî Krishna left for the spiritual abode, the age of Kali commenced.
The verb ‘ प्राहु: is the most critical (12:2:33).
It can be translated to mean…
Say, state, understand (it to mean), assume (it to be so), assert, opine, etc.
If we understand it to mean as ‘assert’ then, Bhagavad Purana is silent on the corresponding (and required) evidence.
The appropriate translation is thus…
“The historians (पुराविद – knowers of the past, ancient times) say/state/assume (प्राहु) that the Kaliyuga began when Krishna passed away.”
[Here are few of my translations of this key verse, in ‘Marathi’
पुराविद (इतिहासाचे विद्वान ) असे म्हणतात कि कृष्ण निधनाच्या दिवशीच कलियुग सुरू झाले
पुराविद (इतिहासाचे विद्वान ) असे समजतात कि कृष्णनिधन झाले आणी कलियुग सुरू झाले
पुराविद (इतिहासाचे विद्वान ) असे म्हणतात कि कृष्ण निधनापासून कलियुगाची सुरुवात झाली]