It's worth noting that a lot of the dates mentioned in this article are far from the scholarly consensus on the matter; to take one example, the attribution of the Puranas to Vyasa is roughly similar to the attribution of the Pentateuch to Moses; it's not a reliable foundation for dating the texts (which most scholars place far later than 1000BCE.)

Similarly, the claim that Pythagoras was acquainted with the Upanishads is not historically attested; there's some fascinating work (by McEvilley) on cultural diffusion between the Ancient Greek and Ancient Indian worlds, but much of it is conjectural, and there's no "smoking gun" to support blanket statements of the type "Pythagoras read the Upanishads."

Finally, in my reading of the secondary literature, most scholars reverse the chronology in the statement "Philosophical formulations concerning Shunya - i.e. emptiness or the void may have facilitated in the introduction of the concept of zero." The consensus seems to be the opposite-- that the concept of zero in mathematics appears to have influenced the philosophical formulations around emptiness.