You might be interested to know that Buddha's birth, activities, mother's name and birthplace are mentioned in the Bhagavat Purana, which was first set into writing around 3000BC, not long after the war recounted in the Mahabharat.
In another Purana (called the Bavishya Purana, about future events - Jesus and Mohammed are both mentioned, as well as Queen Victoria. That Purana is also from around the same time period, maybe a couple hundred years later.
Sanskrit isn't even that old. You'll find the Purana is more recent.