The Vedas and the oldest, the Rig Veda, were composed as oral poetry and memorized. We don't have the first evidence of writing in India until inscriptions usin

The Vedas and the oldest, the Rig Veda, were composed as oral poetry and memorized. We don't have the first evidence of writing in India until inscriptions using the Brahmi script from the edicts of Ashoka around 300 BC. Even then, it would be centuries before large bodies of spoken word such as the Vedas and the Pali Canon were committed to writing. Of course there's the the Indus Valley script, but theres no real evidence to suggest that it was used to write significant and lengthy works. Especially since the IVC collapse would have predated the migration of the Aryans. But there actually doesn't need to be a common writing system, since we know for a fact it originated independently in two places, the Sumerians and the Maya. It's less clear cut (no ocean separating) but it's likely the Oracle Bone script in China was independent too.