@Joe Shearer got a question for you.
I know that Europe was populated by waves of Indo-Euro invaders (Celts, Latin, Germanic, Slavic etc.) over centuries, so was Western Asia (Medes, Persians etc.).
How many waves of Indo-Euro invaders/migrants came to the subcontinent since the Vedic people arrived (assuming they were the first one)? The Jats would be a latecomer right?
@Tergon18 feel free to chip in.
Disagree. Language carries culture. Flow of language is accompanied by flow of culture.
Back a day earlier, so I'm piling on.
First, may I say, with genuine pleasure, that it was nice to see you posting this? I had gathered a melancholy impression that your view was more or less that of Colonel Custer, that the only good Indian was a dead Indian, and that nothing in the nature of these essentially historical discussions was worth the sheer pleasure of a knee in a random Indian middle. Clearly, going by these astute questions, I was wrong. A happy situation. I love being wrong in these things.
Coming to the waves of invaders in western Europe, let me answer by painting a word-picture, without doing the heavy lifting, in the interests of promptitude. Permit me, if you will, to do the same for the western Asia case. Some of this may turn out to be terribly wrong, when I return to the books later, afterwards; apologies in anticipation.
Taking the Greeks first: yes, they came in waves. The Achaeans first, destroying the Cretan and pseudo-Cretan cultures, and paving the way for the Ionians and Aeolians. The Dorians last, and prevalent over all the previous races
(they had iron swords, their predecessors bronze ones; might have made a very big difference). It is worth remembering also that the authochthones, the people of the preceding culture, remained and were recognised by their different speech as late as Herodotus.
The Latins? Far more confusing. We know that the Etruscans preceded them, but we have no idea about the time-sequence of their coming to the Italian peninsula. At this distance, it looks like one agglomerated mass.
The Celts, then. They certainly formed the recognisable mass of 'European' culture, from the reaches of Iberia, contemporary Spain and Portugal, through France, with its 'indomitable' Gauls, and the entirety of the British Isles, Ireland, Scotland (with variations between Pict and Scot), Wales and central 'England'. Did they come in waves? I have to confess that I don't know, not having studied the subject as deeply as I ought to have. Honestly, I only know that the Romans found the cis-Alpine Gauls a handful, and the trans-Alpine Gauls too strong for them, as they defeated and sacked the city several times. It was only with Caesar that they were finally subdued and crushed.
The Germans, on the other hand, provide strong evidence with which to respond to you. Before going further, do note that it is assumed that the different races may have preceded or succeeded each other, but except for the very late date of the Germans, it is not clear if the Greeks, the Latins or the Celts came first or last or in which sequence. What we do think to be true is that the Germans were probably the last. I have also tried to look at each race by itself, and see if 'pulses' were there to be detected; in the case of the Greeks, they were.
Back to the Germans, as they were then, not as they are today.
The difficulty even with this relatively well-documented race's comings and goings is that the good documentation is good relative to the murk and mist covering the origins and the movements of the others - the Greeks, Latins and the Celts. We know that the Romans found them after they swept through Gaul and came to the Rhine, and gingerly penetrated the northern forests. But what they found, what we now know, is still very obscure. Let me pause here, please, largely to catch breath!
To be continued:
The Germans, their tribes, and the sequence of their coming into the Roman Empire;
The question of waves of immigration of such tribes in west Asia;
The question of waves of immigration of such tribes in sub-continental India, and some speculation of what happened before.