The diffusion of Indo-Aryan languages:
The present model is that a small croud of Indo-Aryan elites forced their language on native Dravidian, Munda speakers. I shall remain sceptic of this "elite dominance" model until I'm clear about,
1. If Vaidiks found any linguistic difference between the native poulations and themselves as they entered North-West of India.
2. The relation between Sanskrit and Prakrit
3. Antiquity of Prakrits vis-a-vis Vedic Sanskrit
Until then, I am proposing the following expansions inside India:
Linguistic groups Major Haplogroups Region
1. Mundas R2, L, O North and East India
2. Burushos R2, R1a1, H1 North-West India
3. Dravidians R2, L, R1a1, J2b2, F, H*, H1 South-West India
4. Semites (extinct) J2b2, J2a Near East
5. Prakrits(IA) H1,R1a1, L West-Southern Central Asia
6. Vaidiks(IA) R1a1 Kurgan or Central Asia
Marathis, Who are they?:
The first kings(Shatavahana) that ruled the region of Maharashtra supported Prakrit. However, the later kingdoms of Chalukya, Rashtrakuta were identified with Kannada language and culture. And the Sevunas(Yadavas) were equally supportive of both Kannada and Marathi.
What was the major language in the region of present day Maharashtra?
Some people believe the language closest to Kannada was later supplanted by Indo-Aryan Marathi. I'm not so sure when the dominant Marathas are predominantly Haplogroup H. In fact, I have read that Marathi came into prominance as Maratha tribes became dominant. I suppose unlike Gonda tribes, these Maratha tribes were in fact the later Prakrit migrants to Central India.
Multiple migrations in a slight different way:
I would say, there was a single migration of the people carrying Vaidik culture and they were predominantly Haplogroup R1a1 from Kurgan areas. Multiple migration of this people would have clearly left some kind folklores, at least, from the later migrations especially consdering they had kept their religious traditions in tact by oral traditions for almost a millennium after entering India. Therefore, it shows the dominance of the native North-West Indians among these Vaidiks and minority position of the original Vaidiks.
In my opinion, before the arrival of Vaidik people there were multiple migrations from Haplogroup H1 tribes from Iranian or Kurdish area to North-West of India or deep into India. The people who moved South lost their language due to emerging Dravidian cultural life. However, in North, East and Central India these H1 Prakrit tribes survived because of emergence of Vaidik culture as both Sanskrit and Prakrit were hardly diverged much around 3500 years ago. However, it's impossible to believe that Sanskrit could have spanned so many Indo-Aryan languages in North India considering the fact that it was always made unavailable to the common people. However, non-Vaidik Prakrits did not have any such purity ideas.
I suppose skin colour lightened even among Indo-Aryan , Prakrit, speakers of Iran, Afghanistan much later.
None of the major Haplogroups in India, H1, R1a1, R2 and J2 show a uniform cultural, linguistic patterns. Therefore, not only racial models of cultural/linguistic patterns fail miserably, even the linguistic models of invasion and elite dominance harldy explain the complex scenarios(like that of Marathis) of Indian past history.