That’s the Anasazi episode, season 2.

I asked ChatGPT and here is the answer. I useally hate using too much AI, but when it comes to remembering scenes from movies or shows I had a good luck with it. So hopefaully this helps you find what you are looking for. By the looks of it, its correct.

Yes — you are remembering a real scene, and it is from a canonical X-Files mythology episode, not the Mandela Effect. Here’s the actual reference and where it happens: The Episode You’re Thinking Of The scene you’re describing — where information that someone wanted destroyed is preserved through the oral tradition of a Native American tribe — occurs in the mythology episode “Anasazi” (Season 2, Episode 25). (https://en.wikipedia.org/wiki/Anasazi_(The_X-Files))

In Anasazi, Mulder comes into possession of a secret, encrypted Defense Department tape containing explosive information about UFOs and government conspiracies. At one crucial moment, a Syndicate member asserts that the tribe’s elder, Albert Hosteen, has passed the relevant knowledge to many others by word of mouth, meaning it can’t be completely erased by burning the tape — unless “you kill every Navajo living in four states.” This is essentially the theatrical reveal you remember about information surviving through oral tradition.

This line has become somewhat iconic among fans because it underscores the durability of spoken knowledge versus fragile physical records — and it’s very much part of the official mytharc.

Why You Might Not Find It Easily:

• Anasazi isn’t a Monster-of-the-Week; it’s a mythology episode packed with plot twists and government conspiracy.
• Most episode summaries focus on the encrypted boxcar, Navajo code talkers, and the cliffhanger ending — the “oral tradition” line is in dialogue rather than plot synopsis, so it’s not always mentioned in episode guides or quick wikis.