Sanskrit was a spoken language around 2 millennium BCE (4 000 years ago). Already at its time it was considered a high-register of the language, with the lower registers being called "Prakit".
Its special significance lies in the fact that it was attested very early; but other than that it was similar to any other spoken language.
the earliest form of Sanskrit we know is Vedic Sanscrit, and it must have spit away from other Indo-Iranian languages at some point.