I am an Indian, so I know the India side of this debate fairly well. One of the "big questions" here is why we never recorded history or treated it like a science, despite being one of the oldest civilizations on Earth and being relatively very advanced in fields like Grammar/Linguistics or Mathematics or Philosophy. This was not due to a loss of material or inability to keep record, since we preserved much older texts just by oral recitation (c.f - the Rigveda dated to approximately 1200-1500 BCE~ preserved down to the last pitch accent). In fact, our preservation of the Rigveda was so good that modern linguistics relied heavily on it to reconstruct Proto-Indo-European (spoken approx in 3500-4500 BCE). Around 65% of the PIE cognates are reconstructed with the aid of Sanskrit. Now, our scribes managed to preserve enough of Classical Sanskrit literature as well, quite faithfully. It seems as if our Purāṇas combined with our dynastic vaṃśāvalī-s (pseudo historical records of kings) served a quasi-historical role but we never developed the science of historiography. Why?

Note: There is one exception here. Kashmir is the only state in India that does have a fairly faithful historiographic tradition, (c.f - Kalhana, Jonaraja and the Rājātaraṅgini). Any thoughts on this?

Coming to Iran, I know a small bit of Iranian history but not enough. From what I know, our Iranic cousins & neighbors do not have any historical chronicles either (say from the Achaemenid Period). Why is this so? Why do we rely so heavily on Greek or Chinese or Islamic era chronicles for Indo-Iranian history? Is this possibly due to some ancestral cultural attitudes as the Indo-Iranians had almost an identical religion and language when they split apart. Possibly some common revulsion to history as too materialistic? I don't know, so I ask you all and hope I get some good answers.

Cheers.