Things like the Vedas (or Genesis, Greek myths, American Indian creation stories, &c) aren't precise. Sometimes they're retellings of actual events, distorted by being orally passed down through many generations, sometimes they're just made-up stories.
Sometimes we can correlate the stories with physical evidence. If for instance a particular tradition mentions a king of Babylon named Ashurbanipal https://en.wikipedia.org/wiki/Ashurbanipal and archeologists excavate the ruins of Babylon and find lots of clay tablets &c mentioning him, we can reasonably conclude that there indeed was such a king. (But we'd conclude that from the tablets even if we didn't have the story...)