Here is a transcript of a 1999 lecture by Romila Thapar. She examines quite well the substantive evidence for the Indo-Aryan migrations into the Subcontinent in the second millennium BCE. Definitely worth a read for anyone interested in the topic (transcript has a few typos). Also see my earlier post, which I hope to turn into a more polished article, incorporating all that I have learned since about the topic.

Let me begin by saying the obvious, that the Aryan question is probably the most complex, complicated question in Indian history. And it requires very considerable expertise in handling both the sources and the questions that arise. The expertise consists of knowing something about at least four different fields, first of all archaeology, because a lot of the remains, of almost all the cultures, come to us from excavations and there is the continual attempt to try and identify such cultures with the Aryans…. I mean that it is not enough simply to say that you pick up a list of items from excavated sites and say that the Rigveda has some items, therefore … they are identical cultures. When I talk about archaeology I am also talking about the way in which the total society functions and how these elements are integrated.

The second area of expertise is linguistics and here I would like to emphasize, very strongly, that it is not enough merely to know Sanskrit to be able to say that you can handle the questions that come up in the interpretation of the Vedic texts. There is now, since the last thirty years, there has developed a huge body of information which comes from a discipline called linguistics. Those in this discipline do comparative studies of different language structures…

The historical context, this relates to a whole series of questions, how society is defined in the past — agro pastoral, agrarian, urban… What is the meaning of these terms? What is the interaction between ecological, social, economic, cultural, religious forms? These are all aspects of a historical problem and when you are studying a total problem like the so-called the Aryan question you have to go into the interaction of all these different aspects. Is there a difference between a cattle rearing society and a society which carries out overseas trade? And these are fundamental questions in historical analyses. You cannot avoid them. You cannot just say there is reference to cattle in the Rigveda and cattle are depicted on the Indus seals therefore there is a similarity. It is the function. The function, both the actual function, the ritual function, the role that cattle play in a particular society in terms of its economy, its rituals and so on.

And the fourth discipline which I think is important … is social anthropology…