[throwaway7312]

Uncontacted tribes in the Amazon likely wonder the same thing. It's such a big Earth, yet only a few hundred humans are known to exist.

Why are there no other detectable signs of human life, like smoke signals, territory markers, or emissaries from any more but a handful of other tribes? Surely if advanced humans existed, they would have contacted these tribes by now, to share technology, discoveries, and medicine. Yet they haven't.

How can the whole planet be so... silent?

[chongli]

If they're not aware of any other humans (let alone all the cities out there) then they're likely not aware of the actual size of the earth. Perhaps they only consider it in terms of the surrounding territory.

[riffraff]

I understand the point that we might be too backwards to see the signs of hyper-advanced civilisations, but how is it that _all_ the other civilizations are super advanced to the point that any trace they leave is impossible to understand?

And, won't uncontacted tribes in the amazon have seen airplanes and such?

[ripsawridge]

Uncontacted tribes in the Amazon are not really uncontacted. They are the way they are by preference.