shiv wrote:A_Gupta wrote:https://www.theatlantic.com/international/archive/2016/01/difference-between-language-dialect/424704/
What's a language, anyway?
With this above as background, I'd say, emanating from the Saraswati-Sindhu region, via largely cultural influences, not permanent movement of people, but perhaps aided by the peregrinations of pastoral peoples, there grew to be this continuum of related dialects stretching eastwards into the Ganga-Yamuna plains, and westwards into Central Asia and the edges of Europe (kind of as show in Robin Bradley Kar's diagram). When exactly? You figure out the dates. This is the root of the Indo-European language family.
At some point, there was a movement of people from Central Asia into Europe; the IE invasion there seems archaeologically and genetically established.
Plausible
About that Atlantic link above - I liked what I read though I did not read it all. I think what gets forgotten in discussions of languages is that Europeans saw languages as nations. Lots of old definitions of nation claim language as the unifier - at least for Europe. Hence India was many nations. That said - for 19th century philologists Sanskrit suddenly created one superior Christian nations of descendants of Japheth that displayed greater antiquity than the hated Semites with their descendants in the Levant/Assyria. The Aryans of India who went there from Europe, with their great language were "fallen people, corrupted by black heathen Dravidians.
The dates for Sanskrit that were fixed back then - 1500-1000 BC have never change. History has compressed itself as and when needed to fit that date.
European took "internal evidence in the Vedas" to conjure up "Aryans" and "dasyus". The took one word "horse" and one verse (10:18) about burying a man to connect with graves in Eurasia. But they did not want to look at "internal evidence" of the Vedas speaking of a Saraswati river.
If I look at internal evidence of the Vedas that speaks of a forested environment and a river reaching the sea in the area where the Saraswati is said to have been and then I look for modern research papers on palynology and palaeogeology I find that the last time that area was thickly forested and featured a river going all the way to the sea, it was 10,000 years ago (8000 BC).
Look at Manusmriti: This mentions Vinasana - where the Saraswati disappears in the desert. That actually happened between 9000-6000 years ago (7000 to 40000 BC). Nilesh Oak's date of 5560 BC for Mahabharata fits in well with this. But Manu also speaks of lots of forest products and advises students to wear either deer skins or clothes made of flax or hemp. Cotton gets a mention but not as fabric. So Manu is after cotton (7000 BC) but before Harappa.(3000 BC)
Harappa was arid. Not forested other than seasonal desert scrub. Practically no deer bones found in Harappa - so very unlikely that generations of students were wearing deer skins. Harappans wore cotton and silk.
So we are probably looking at a Vedic culture that started developing 10,000 years ago. In fact I would suggest that there is no point looking for evidence of Vedic lifestyle in Harappa, Its like looking for that in modern Bengaluru.
If you were to look at the woods hole study published sometime back it says that saraswati river started breaking up around 3000 BC. That is when the lakes started forming according to this paper.
Did the Indus Civilization provide the chariots, which they built exclusively with tall, fair-skinned riders in mind? Or was it that the Indo-Aryans mastered the technology and resource management for chariot building, but somehow no other industrial or economic activity at all, while watching sheep mount each other on the steppe? 
