· There are two types of Yugas, the 5 year Yuga for ritualistic purposes and the Catur Maha Yuga running into lakhs of years.
· The Catur Maha Yuga is of two types, one running into a fixed duration of lakhs of years and another of shorter duration identified by the nature of Dharma running in different proportions in each of the four yugas.
· In the Dharma Yuga scale, a Yuga is followed by a period of Sandhya and then Sandhyamsa. The dharma of the Yuga declines by three-fourths in the Sandhya of that Yuga. The reduced Dharma of the Sandhya period further gets dwindled by three- fourths in the Sandhyamsa of the Yuga. When that decreased level of Dharma continues in Sandhyamsa, it marks the birth of the next Yuga having that portion of Dharma as the Dharma of the next Yuga.
· This description given by the Puranas are helpful in understanding the verses of Srimad Bhagavatam on the start of Kali Yuga. Kali Maha Yuga (of lakhs of years) started at the exit of Krishna, but the Kali Dharma Yuga started 2526 years after the exit of Krishna. At that time, the Saptarishis were crossing the star Magha. The Nanda Dynasty started then, says Bhagavatam.
· No standard duration of time has been given by the scriptures to the extent of Sandhya and Sandhyamsa of any Yuga. Only the level of Dharma decides the duration of these two.
However a definite time line for the start of the Treta Yuga has been given by the Puranas. There is also an inscriptional evidence for the split up of the Yugas coming after this starting date of Treta Yuga. We will discuss them in this part.
The date of the onset of Treta Yuga
The two Puranas – Vayu Purna and Brahmanda Purana have given certain specific features for the onset of Treta Yuga. The following is produced from Brahmanda Purana.
The creation of rain!
By the statement of creation of rainfall resulting in the growth of plants, definite clues are given about the climatic epoch preceding the Treta Yuga. For further confirmation let us see what Vayu Purana has said.
The arrival of rainfall is being told as a special occurrence in both the Puranas for the onset of the Treta Yuga. The resultant growth of vegetation and the subsequent cultivation practices heralding a new way of life shows that the rainfall started occurring regularly. This is a significant hint owing to the fact that the monsoonal rainfall started only in the beginning of the current Epoch of Holocene that commenced 11,650 years ago. Until then the climate was very cold due to Ice Age and Younger Dryas (mini Ice Age). It was already written in Part 6 that the Sun Vivasvan became Mārtanda during Younger Dryas (12,900 to 11,700 BCE), temporarily blurred by the comet fall.By 11,600 BCE the atmospheric debris settled down giving way for the sun rays to heat up the earth. This sun is recognized as Vivasvan, the sun of the current times.
Geologically this epoch of this sun is known as Holocene. The increase in insolation caused many episodes of deglaciation and the heating up of the oceans churned up monsoonal activity for the first time after thousands of years of dormant climate of the Ice Age. Some people tend to think that India was not affected by the Ice Age. It is not so. The Himalayas were within the glacial boundaries of the Ice age with many glaciers building up on the peaks. There was no River Ganga then. The river Tapati was also not flowing then (part 6) which means including the Vindhya Range it was terribly cold to the north of it. The sea level was below 120 meters than it is now causing the low level coastal plains well exposed above the sea, making them fit for living.
Many scientific studies have been done on many regions of the world to assess the arrival of monsoon rains in the respective regions. For the South west monsoon of India (SWM), there exists a study by Overpeck, J., Anderson, D., Trumbore, S. et al, giving specific time periods of monsoon intensity in India. The data from this study is crucial for arriving at the begin-date of the Treta Yuga in Dharmic scale.
The relevant part of the abstract is reproduced
refers to Kilo annum meaning 1000 years. To be understood as ‘1000 calendar
The first onset of the SWM happened 13,000 years ago (11,000 BCE) and lasted for 500 years. The second onset was 10,000 years ago (8,000 BCE) and this also lasted for 500 years. Perhaps the SWM was struggling to stabilize in this period. Closely following this, the monsoon activity intensified for 4000 years starting from 9.5 ka, i.e. 7500 BCE. This lasted until 3,500 BCE. The data is available till this period of the Mid-Holocene.
A clear chronology emerges from this.
Stage 1: 11,000 to 10,500 BCE
Stage 2: 8,000 to 7,500 BCE
Stage 3: 7,500 to 3,500 BCE
This monsoon (SWM) arrived from the south West of India crossing the Arabian Sea and the Western Ghats. The Deccan plateau and the North Indian states located to the south of the Himalayas are the beneficiaries. This monsoon doesnot benefit much the Saraswati region.
The Saraswati region had a different rainfall pattern called the Western Disturbance (WD) coming from the West of India, from the Mediterranean region in the winter season. It benefits the North West Indian regions where the River Saraswati was flowing. This rainfall pattern was present even before the Holocene, i.e. before the birth of the present Sun, Vivasvan. The episodes of this rainfall documented by K. S. Valdiya gives the following chronology.  (BP refers to Before Present)
Heavy rains: 15,300 to 14,700 BP (13,300 to 12,700 BCE)
Heavy rains: 11,500 to 10,800 BP (9,500 to 8,800 BCE)
Very Heavy rains 3: 9,500 to 5,500 BP (7,500 to 6,800 BCE)
Weaker rains: 8200 (6,200 BCE), 6000 (4000 BCE), 5000– 4300 (3000 to 2,300 BCE)
A combined data of the two rainfall systems are tabulated below to arrive at an understanding of the pattern to locate the beginning of Treta Yuga.
South West Monsoon (Deccan, N.India)
Western Disturbance (NW India, Saraswati)
13,300 to 12,700 BCE
11,000 to 10,500 BCE
9,500 to 8,800 BCE
8,000 to 7,500 BCE
7,500 to 3,500 BCE
7,500 to 6,800 BCE
3000 to 2,300 BCE
(No data available for SWM for serial numbers 6 -8)
The data shows that WD facilitated copious flows into the river Saraswati before Younger Dryas period. There was a decline in WD during Younger Dryas (10,900 to 9,700 BCE). This is supported by the sedimentary analysis of Khonde et al establishing the presence of a Sub-Himalayan river draining into the Rann of Kutch 10,000 years ago. Rest of India was devoid of rainfall through all this period. Vivasvan was not yet born in this period, thereby ruling out the emergence of Vaivasvata Manu till then. In other words, though the river Saraswati was flowing until 12,700 BCE, no Vedic society flourished then. The period of Younger Dryas ending around 9,700 BCE did not see the Vedic society.
At that time there was no Dandaka forest. From the Uttara Kanda of Valmiki Ramayana, it is known that the region between the Vindhya and Saivala was a desert in the Krita Yuga. No forestry existed in this region of the Deccan plateau. Graham Hancock’s maps testify the absence of forests in this region. Similarly there was lack of vegetation in Saraswati region, in tandem with cold and dry conditions of the Ice Age.
The first rainfall hit the Western Ghats and the west coast of India only around 11,000 BCE. Going by the Puranic version this must have triggered the first natural vegetation of Bharatavarsha. This is corroborated by the vegetation maps of Graham Hancock.
The following map from his website shows grasslands in 11,500 BCE but growth of rain forests within a thousand years from then, matching with the monsoon study.
The first rainfall however did not continue for long. It lasted for 500 years, until 10,500 BCE. This period is marked with an important event in the history of Bharatavarsha.
Manu entered Bharatavarsha, pushed by the first floods in the Arabian Sea
The first rains of South West Monsoon must have disturbed the coastal habitats on the western coast of South India. The underwater discoveries in the Gulf of Cambay dated at 9000 BP (7000 BCE) and in Srivardhan off Maharashtra dated at 6000 BCE offer evidence for habitations in the extended coastline on the western border of peninsular India. Habitation was very much likely throughout the stretch of the western coast even during Younger Dryas.
Around the time of first episode of SWM, there was a significant increase in deglaciation in Antarctica. That was towards the end of MWP1A (Melt Water Pulse 1A) corresponding to 11,800 BCE and afterwards.  Episodes of icebergs falling into the sea near Antarctica could trigger sea floods gushing northwards and entering the Arabian Sea. With the first rainfall lashing the west coast simultaneously, the disturbed habitants of the coastal region could move northwards along with the flow of the sea floods and enter the estuary of the River Saraswati. The reverse current of the floods had taken them to the origin lake of the river in the Himalayas. And thus entered a people headed by Naubandhan (today known as Haramukh) read from pages 26- 30 in my paper HERE. The location map is reproduced from my paper.
Since Manu's period is associated with Krita Yuga - a version reiterated by the inscription furnished at the end of this article, it is inferred that Krita Yuga was running when the first abrupt showers happened. Around 10,500 BCE the Krita Yuga was running.
From the data of the Table it is seen that rainfall at the River Saraswati basin had picked up following this date. Between 9,500 to 8,800 BCE Saraswati was well fed by WD. The Rig Vedic culture had flourished at the Saraswati region in this period. The Puranic version of the beginning of Treta Yuga with the arrival of rainfall, matched well with this long duration of rainfall when the Vedic culture also flourished simultaneously. It is reasonable to assign 9500 BCE as the beginning date of Treta Yuga.
Soon after he landed inside Bharatavarsha,Vaivasvata Manu had explored most regions of North India for suitability of habitation. This is corroborated by the verse of Valmiki Ramayana that Vaivasvata Manu founded the city of Ayodhya for the Ikshvakus. This implies that the Rig Vedic sages did not stay in the Saraswati region alone; they had spread throughout North India soon after they entered through Saraswati. Settlements were made by devising units of measurement (Vaastu principles), says Vayu Purana. Varna and Asrama dharma were laid down in this period (beginning of Treta Yuga) by Manu and the Saptarishis.
The Puranas do talk about a second bout of rains in concurrence with the scientific data on the second episode of SWM after a gap of 1500 years in 8000 BCE. In the first creation of the rains, crops sprang up. In the second creation, rivers started flowing. They must have been the rivers of the Deccan and North India. During this period the until-then dry Dandaka region became thickly forested.These rivers were rain-fed, meaning to say, not fed by the melting snow of the Himalayas. The following verses from Vayu Purana testify this.
River formation and settlements on the banks of the river had happened after this second spell. This was possible after 8000 BCE when monsoon intensified. A significant finding of the study helps us to time the Himalayan Rivers, particularly the Ganga! It says that though the solar insolation increased, the intensification of SWM occurred 3000 years later corresponding to the period 7500 to 3500 BCE.
Insolation forcing determines the rate of change of ice volume but not its magnitude. The increased insolation forcing 3000 years before SWM intensification in 7500 BCE could refer to the rate of melting of the glaciers of the Himalayas. No study seems to have gone into checking this feature in Gangotri; however a combined reading of rain-fed rivers (Puranas) and the intensification of the SWM around 8000 BCE (3000 years later than the peaking insolation forcing) suggests the breaking of the Himalayan glaciers only around that period. The probable birth of the River Ganga could have been between 8000 and 7500 BCE (This is subject to further cross referential studies by this writer for the Chronology book planned at the end of the year)
Seventeen classes of seeds in the wild were grown naturally in Treta Yuga. They include rice, wheat and barley. Seasonal flowers also were growing.
But then came a time they were cultivated by human efforts. Along with that came the necessity to protect what one created. That gave rise to the development of Kshatriya hood for the first time in Treta Yuga.
This Puranic version of cultivation finds corroborative evidence in the archaeo-botanical studies in trans-Sarayu region and stretching upto the northern fringes of the Vindhya Range. It gives us a time frame of when this happened.
Initially wild rice was available in nature. The earliest evidence of wild rice starts from early Holocene in Lahuradewa. This is followed by domesticated rice from 8th millennium to 6th millennium in Koldihwa and Mahagara in Allahabad. Son Valley in Madhya Pradesh has shown rice cultivation from 6th to 5th millennium BCE. The Treta Yuga locations of cultivation are shown in the map.
[Rice cultivation had spread from east India to the Indus regions in the west. Petrie et al in their paper established that rice was cultivated in Rakhigarhi even before the Indus Urban phase. They observed that proximity of this region to the Ganges where the earliest domestication of rice was found in 7th millennium BCE “prompts the re-evaluation of the role of rice for Indus populations, and the way that it was transmitted from farther east”. This is a direct challenge to the view in support of AIT (Gangal et al. 2014) that farming entered India through Iran and Central Asia] 
Then a time came when crops could not be grown easily, implying the complete exploitation of the natural nutrients of the land. This resulted in manual efforts to find newer lands and methods of cultivation. This signaled the end of Treta Yuga.
The avatāra of Parashurama wielding an axe was basically to clear the forests to make way for habitation and also land for cultivation. In this period Rama of Ayodhya also lived. North Indian rice-growing regions discussed above were home to the Ikshvāku-s of Sarayu, Kushikā-s of Vishvāmitra and Jamadagni-s of Vindhyas – the last two being Rig Vedic sages having close blood relationship. Jamadagni was Vishvāmitra’s sister’s son and they both were of same age. This period was the Sandhi period of Treta and Dvapara Yuga when the Kshatriyas were destroyed by Parashurama, the son of Jamadagni.
The Sandhya is identified by two factors here – cultivation with manual efforts and the mix of Rajasa and Tamasa guna. The lower limit of rice cultivation as per currently available studies help us in identifying the lower limit of Treta Yuga. Son Valley in Madhya Pradesh has shown rice cultivation from 6th to 5th millennium BCE. This region was occupied by Jamadagni. Evidence of rice cultivation in this region, later than the northern regions could perhaps be due to the search for newer terrains by Parashurama. The upper limit of rice cultivation in this region becomes the lower limit of Treta Yuga. As such Treta Yuga sandhi must have happened in the 6th millennium BCE.
· Following this the Sandhyamsa seemed to have passed quickly giving rise to the birth of Dvapara Yuga in early 5th millennium BCE.
· It had run into 2000 years – in the 5th and the 4th millennium BCE. Going by the scale of Dharma, Dvapara Sandhya must have started with the dice game and Draupadi vastraharan. By the time the war took place, the Sandhya period was well settled with 1/4th of Dvapara Dharma.
· At the time of Parikshit, the decline in Dharma was arrested by him leading to the extension of the Sandhya period.
· The early Harappan being Post-Mahabharata, the smooth functioning of the trading events justify the role of chastisement, crucial for the maintenance of the Yuga Dharma.
· Until the time the Harappan culture declined in 1500 BCE corresponding to Yudhishthira Shaka 1601, Dvapara Sandhi had continued.
· The ensuing period witnessed growth of heretic sects that marked Dvapara Sandhyamsa. This steadily went on till Yudhishthira Shaka 2526, when the Nanda Dynasty started ruling.
· As per Srimad Bhagavatam Kali Yuga in Dharmic measure had set in at that time. This was 575 BCE.
· The growth and prevalence of heretic sects in Dvapara Sandhyamsa becomes the Yuga Dharma of Kali Yuga.
· The scope of heretic sects displacing Vedic culture increases day by day in Kali Yuga.
· Additionally the Scriptures getting mis-interpreted are the dominant features of Kali Yuga.
· The very date of Kali Yuga getting manipulated is something unthinkable before the Mlechas started interpreting our texts. Now the Mleccha behavior has been taken over by the natives of the Dharma which was at its peak 10,000 years ago.
These sequences solve the mystery of why the scriptures repeatedly have said that the Yuga system is applicable to Bharatavarsha only.
· The growth of this culture started with the arrival of rainfall. The particular sequence of events had followed the SWM of Bharatavarsha. This sequence is not the same everywhere. With rainfall giving rise to vegetation and rivers facilitating habitats and the allied growth of Varnasrama and Asrama dharma for the functioning of a community and for individual growth, the dharma based Yuga classification is applicable ONLY to Bharatavarsha!
· This Dharma based classification also solves the doubts about the feasibility of too many cycles of Yugas in the past with names of people being mentioned by the sages. For example we are in the 28th Catur Maha Yuga when Krishna Dvaipayana had compiled the Vedas at the end of Dvapara Yuga. The current Catur Maha Yuga cycle had existed for only 13,000 years. Rainfall had become the basis of the development of Dharma. This rainfall is cyclical along with the globally alternating cold and warm conditions. The probability is very high for several rounds of fresh arrival of rainfall in a parched land giving scope for newer cultures to flourish. As such we are in the 28th round.
· The pattern of Dharma seeming to be decided by rainfall and the allied sequences, it seems to have been suggested that human civilization could have peaked as in Ramavatara when Rama stood as an epitome of all virtues and declined as it happened in the dice game of Mahabharata and reeling towards a point of no return as in Kali Yuga of current times. As such Rama and Krishna and Mlecchahood of Kali Yuga keep repeating every time this Yuga cycle gets scope for development.
· Bharatavarsha becoming the epicenter for this cycle, the climatic conditions of the past might give us a rough idea about when the past cycles of Yuga had occurred.
The timing of the sequences starting from Holocene is reflected in the Yuga classification found in the Tiruvalangadu copper plates of Rajendra Chola I issued in the 10th century CE. The Yuga period of the past kings of the Chola lineage mentioned in the inscription is comparable with Rama’s lineage. (The Cholas claim ancestry from Sibi and Rama). A tabulation of this is given below.
This inscription is a solid evidence of the use of Dharma based Catur Yuga in Bharatavarsha.
The chronology of Dharma Yuga cycle derived from the Rainfall features is given in a nutshell.
The flood at the time of Vaivasvata Manu (First episode of SW Monsoon)- 11,000 to 10,500 BCE
Krita Yuga - Until 9,500 BCE
Treta Yuga (Beginning of rainfall by WD) - Started around 9,500 BCE
Dandaka Forest formation - From 8000 BCE onwards.
Rain-fed rivers - from 8000 BCE onwards.
Birth of River Ganga - Between 8,000 and 7,500 BCE
End of Treta Yuga Sandhya and Sandhyamsa - 6th millennium BCE
Dvapara Yuga started - Early 5th millennium BCE
Dvapara Sandhya - Late 4th millennium BCE
Kali Maha Yuga Started - 3101 BCE (Dvapara Sandhi in Dharma Yuga)
Dvapara Sandhyamsa - Till 575 BCE (till Yudhishthira Shaka 2526)
Kali Yuga - 575 BCE onwards
Whenever we come across Yuga Dharma in a passage, we must assess the context to decide if it is about Dharma based Yuga. In the Dharma based Yuga, the Sandhya and Sandhyamsa offer hints on the extent of the degradation of virtue to gauge the probable onset of the next Yuga.
This is completely different from the Catur Maha Yuga of lakhs of years, though it is possible for the Dharma based Kali Yuga to come to an end anytime within this Kali Maha Yuga and a new cycle of Dharma based Catur Yuga to make a beginning. The Catur Maha Yuga of lakhs of years is determined by the planetary conjunctions and described by the Siddhantas. The conjunction was witnessed only once after the concept was formulated. That was at the time of Krishna’s exit when all the planets except Rahu congregated at the beginning of Aries. That date can never vary given the fact that it follows mathematical precision. We will discuss it in the next part.
(To be continued)
 Brahmanda Purana: 1-2-30
 Vayu Purana: 1-8-79
 Overpeck, J., Anderson, D., Trumbore, S. et al. The southwest Indian Monsoon over the last 18 000 years. Climate Dynamics 12, 213–225 (1996). https://doi.org/10.1007/BF00211619
 K. S. Valdiya, “The River Saraswati was a Himalayan-born river” CURRENT SCIENCE, VOL. 104, NO. 1, 10 JANUARY 2013
 Khonde et al, (2017) “Tracing the Vedic Saraswati River in the Great Rann of Kachchh”
 Valmiki Ramayana: 2.71.17
 Vayu Purana: 1-8
 Vayu Purana: 1-8