@Golden_Rule &@Arvind
You gentlemen are conflating history and mythology - two different topics . History as we understand it today is different from itihasa of Vedic times . The former is a discipline which needs verification on the ground - literally through archaeology , textual evidence , linguistics and tertiary sources if any . The latter is a matter of belief . I'm sure you'd understand the difference between the two and see the fallacy of your arguments .
To cite an analogy - The lack of the Big 3 ( as described above ) is the reason why AIT is a theory , nothing more nor less . That's also why the OIT is a theory too . But as theories go , there seems to be a gradual shift towards OIT away from AIT which some of it's proponents are now renaming as AMT , given a gradual uncovering of new evidence , certain new archaeological finds , re examination of old ways of analysis , etc mostly by a bunch of mavericks but not necessarily so .
I guess within a few decades this matter pending since nearly two centuries should see a satisfying conclusion .