‘In the interior parts of the central and southern Indian peninsula, the rain shadow of the Western Ghat mountains contributes to a semi-arid and highly seasonal climatic regime, most of which sees just one rainy season during the southwest monsoon. This region includes much of the state of Karnataka, as well as the Rayalaseema region of Andhra Pradesh, and the more arid maidan regions of Maharashtra.’ [Morrison, 2015 :Archaeologies Of Flow – Water And The Landscapes Of Southern India Past, Present And Future, in Journal of Field Archaeology, 3] That’s Morrison writing in 2015 based on her archaeological field studies in Deccan. 100 years earlier in 1913, the Under Secretary of State for India told the British Parliament :“The western hills have the effect of arresting the lower strata of rain clouds brought up from the Indian Ocean by the south-west monsoon, and of causing excessive rain precipitation on the narrow strip of coast on the western side of the peninsula. … Towards the centre the plateau presents a monotonous and almost treeless extent; water is scarce, and fodder difficult to procure.” (Holderness, 1913 :Statement Exhibiting the Moral and Material Progress and Condition of India …, No. 48, 10)
Probably that has been the condition in trans-Sahyadri Konkan since a long time; and sometimes it has been worse. On the basis of the excavations at Inamagamva (Inamgaon in Pune district) and related sites, scholars are of the view that severe drought affected the trans-Sahyadri region around 1,000 BCE. “Around 1000 BCE people began to leave this village and others in the region.” says Juliet Clutton-Brock. [Clutton-Brock, 2012 :Animals As Domesticates, 89] The Inscription No. 1 at Sravanabælagola records Chandragupta’s sixteen dreams, which Bhadrabahu, the last of the Jainasruta-kevali, interpreted as a twelve year famine between the Vindhya and the Nilgiri mountains, and decided to move the entire Sangha to the south to escape the starvation; that was towards the end of the 3rd century BCE. [Rice, 1889 :Inscriptions At SravanaBelgola, 3]
According to a genetic study, haplotypes of Kanara buffalo were found to have contributed to ancestral haplotypes of toda buffalo, suggesting the possible migration of buffaloes, and possibly the toda themselves, from Kanara region towards Nilgirimountains along the Western Ghats. [Kathiravan, 2011 :Population structure and phylogeography of Toda buffalo in Nilgiris throw light on possible origin of aboriginal Toda tribe of South India, 304]. Kanara here probably does not refer to the coast; it refers to the area across the Sahyadri. Given the estimates of the divergence time of the toda buffaloes from other main breeds in India, the migration is likely to have happened around 700 BCE –200 CE. [Kumar, 2006 :Genetic Variation And Relationships Among Eight Indian Riverine Buffalo Breeds, in Molecular Ecology, 599] The three possible dates for the distress migrations discussed above roughly mark the concluding centuries of the last millennium BCE as a possible period of drought in trans-Sahyadri Konkan.
Based on study of plant pollen, spores and certain microscopic plankton organisms in fossil form, collected from Rajasthan lake deposits, Krishnamurty et al construct the following climatic sequence for the Western and Central India : before 8,000 BCE – severe aridity; 8,000 to 7,50O BCE – relatively wet; 7,500 to 3,000 BCE – relatively dry; 3,000 to 1,700 BCE – sudden increase in wetness; 1,700 to 1,500 BCE – relatively dry; 1,500 to 1,000 BCE – relatively wet; 1,000 to 500 BCE – arid. [Krishnamurty et al, 1981 :Palaeoclimatic Inﬂuences From The Behaviour Of Radio-Carbon Dates Of Carbonates From Sand Dunes Of Rajasthan] According to Shinde, this climatic sequence can be applied also to the larger semi-arid region that makes up Western and Central India. [Shinde, 2000 :The Origin And Development Of The Chalcolithic In Central India, in Indo-Pacific Prehistory Association Bulletin, no. 19, 125] Our earlier estimates of arid period/drought in trans-Sahyadri Konkan would more or less fit around Krishnamurty’s last arid period – 1,000 to 500 BCE.
Berkelhammertraces the variations in monsoon during the period 10,500 to 1,600 BCE using data from a calcitic stalagmite from Mawmluh Cave in Cherrapunji, Meghalaya. [Berkelhammer et al, 2012: An Abrupt Shift in the Indian Monsoon 4000 Years Ago] The basis for such an inference is the observation that there exists arelation between the oxygen-18 (18O) to oxygen-16 (16O) ratio in the stalagmite deposit, and the rainfall during the time it was formed. So, noting the 18O:16O ratio at different points on the stalagmite, the quantitative pattern of rainfall during the period of its formation can be discerned. So based on the Mawmluh Cave stalagmite, Berkelhammer et al conclude that there occurred an abrupt shift in monsoon between 10,500 and 1,600 BCE, the formation period of the stalagmite; that shift was around 2,000 BCE. This seems to be fairly close to what has been called the ‘climatic breakdown’ or 4.2k Event, that occurred around 2,200 BCE, andwhose effects have been detected inthe Middle East, East Africa,southern Europe, southern China, as well as in the tropical Indian Ocean. Berkelhammer’s findings from the Meghalaya cave suggest that this anomaly in monsoon was larger than any before or after it since the end of the last ice age. However, this event does not fit into Krishnamurty’s climatic sequence we have noted above.
Cui and others conducted a similar study in the Godavari basin, using the organic matter and mineral magnetism from a sediment core from the Godavari delta to detect variations in vegetation cover in the catchment area of the river during the period 4,000 BCE and 700 CE. The study shows that the organic matter in the sediment increased from 2,000 BCE, and again from 1,200 BCE; but significantly decreased post-1,100 BCE; this points to a decline in vegetation beginning the last millennium BCE. [Cuiet al, 2017: A mid-to late-Holocene record of vegetation decline…] These findings are in conformity with what we have observed earlier.