In retrospect

Theorists say that there were many migrations in the period. A big invasion was not there. It makes sense too because it aint plausible that Aryans would ransack native (dravidian?) harrappan cities to go all the way down in order to clear forests and start a new 'civilisation'. Harappans are known to have traded with Egypt and mesopotamia-bactria. I won't be surprised if some people crossed the Indus for more 'opportunities'

The battle against AIT guys is more because of the search of Indian-pride than anything else. Just the way AIT was invented to establish the colonial superiority, those opposing the AIT with their rather 'strong' indological arguments, try to prove that most of what Indian culture became is because of stuff that existed in India, much before Aryans might have come. Aryans, like later migrators, didn't destroy it but got established in the pre-existent fabric. According to them, its wrong to say that Aryans were the ones who established Indian culture.

Consequently, sanskrit (something that is known to be literary "exclusively" in India) is not an "Aryan language" and niether are Vedas Aryan (although the sanskrit used in the latter might be different) For that matter, Vedas (in the literal sense) are considered eternal from a Hindu perspective. That is more like the semitic belief that scriptures have been handed over to human by God. It doesn't really matter, if Aryans dominated brahminhood for some time, or were the most ardent contributors to the eternal 'Vedas' (with the four they brought)

Well, AIT has really lost hold in academia. India still has it popular for the sole reason of its academia being dominated by the leftists.

The biggest blow to AIT, in my view was presence of Harappan sites on the erstwhile Saraswati river. Before that, everyone (esp leftist hist) rejected the R. saraswati as yet another disgusting Hindu belief. The drawings on large red pots used in their granaries, are now interpreted as representing some Puranic stories (Hindi: PaurANik). For example, the very belief of soul crossing the river Vaitarni before going to heaven, although present in Puranas is known to be of Greek origin. Since, we know that Harappans believed that and we know that its written in Puranas, there is really no reason to say that Aryans wrote Puranas.

That makes sense too, if you see that puranas or the classical upanisads don't express any spirit of nihilism. Its really hard to believe the big 'invasion'!

Besides, looking from the other side, there is another interesting set of theories that want to prove the preservation of pagan ways in the Roman Christianity that dominates the world. For example, there are a lot of similarities between the practices of Romans and North India's hindu (and I mean, nuu...merous!). Its sensational part kept aside, both civilizations might have shared ideas before Chrisitanity.