The Scientific Revolution Of India Before Muslim and British Conquest

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.