Rigveda is considered the oldest written record of Sanskrit. It has Sanskrit in a very developed form. I wonder if there are any records of Sanskrit before Rigveda which show the language being used for day-to-day activities like accounting etc.
I know its been quite a while since the question was asked, but can't resist from answering it.
Quoting from a nicely written article:
There are historians who conclude that writing was not started during this period as no manuscripts, writing materials or writing instruments have been discovered belonging to this period. But I may beg to differ as although there are no direct evidences, the following points may highlighted.
Rig Veda itself is the evidence. It is a book consisting of more than 100,000 verses and 1000 hymns. Don’t you think that such a vast volume of information, unless written somewhere , we should n’t have these available at present.
Another point, in Rigveda itself the words “Akshara” ( means Alphabet), Grandha ( means Book), Cows with the Numerical “8” written on them are present which clearly indicates that some form of writing was there.
Also it has been written in Rig Veda that Shatapriya states – Vamanadeva by hearts Veda by “seeing” it and also Atreya saying about a Rishi reading it.
Altough nothing about the word “write” is seen in Rig veda , Yajur Veda and Atharva Veda uses the word “ Likha” which means “to write”.
All these indicates writing, though we do not know about where is it written or how is it written. So it should be concluded that some form of writing have been started in India during Vedic age itself.
There was no writing in India before the Mauryan Empire. Sanskrit was a spoken language. Sanskrit writing derived from Prakrit, breaking off around very roughly around 100 B.C. It developed as the official court writing system of the Brahmans, as opposed to the wider system of "common Prakrit", which continued to be used by Buddhist texts and others.
The ancestors of the Iranians may be mentioned in Sumerian texts about the land of Aratta. This was an important region from which Lapis Lazuli and other things were traded. While they are not written records, there are important archaeological sites in teh B.M.A.C. like Godin Tepe. There is even the original site of the chariot warriors, Sintashta.
Since there was no writing in Pre-Mauryan India, there is only oral tradition. The Rig Veda was impeccably memorized by Brahmans. It is a usable record like no other oral tradition in the world. It has given us a perfect form of the Old Vedic language. Before this, we have only linguistics. They have partially reconstructed Indo Aryan from their homeland.
There is also comparative Aryan and Indo European mythology, by which an original religion is tentatively constructed. They can closely be related to people like the Scythians and Medes. In fact, the Medes were very similar to the Vedic culture. These similarities have made its way into Persian and Zoroastrian literature. If you go back further, they can be put in a broader context of Indo European religions. Some of these are Greek, Scandinavian and Osettian mythology.