"Reliably" passing down information for future generations is a recent phenomenon. Just go and look at the history of mathematics and there were multiple periods where information was lost and rediscovered.
We are talking past each other, I would not consider a few religions being able to pass down information about that specific religion to future generations as humanity as a whole being able to pass down information reliably. Especially given that the "Vedas" is wholly useless information while things like the Pythagorean theorem were discovered, lost, then rediscovered. We've only recently rediscovered how Romans created concrete?
Also given humanity has existed for many years longer than 4000 years and 4000 years really only represents 160 generations of humans I don't consider that impressive.
We literally have clay tablets from ancient babylon and books that are thoisands of years old. We have traditional crafts like blacksmiths and pottery that were taught for thousands of years.
https://en.m.wikipedia.org/wiki/Vedas
> The Vedas have been orally transmitted since the 2nd millennium BCE with the help of elaborate mnemonic techniques.
That's at least 4000 years of lossless transmission.