Where do people not wear clothes at all?

To be able to manage to go naked, you'd first need to live someplace where the climate is fairly warm.

Then you'd need to be surrounded by a society where it's acceptable to go naked - and/or where there are no suitable materials available to make clothes of.

Complete nudity has always been rare. Even if the weather and local morals allows it, people have usually managed to find some way of inventing clothes to show who's important.

Today, complete nudity is very rare. Even if you live somewhere where there are no naturally occuring materials to make clothes off, stuff can almost always be imported.

You'd have to go look for some really isolated rain forest tribe to find some.

But once upon a time, people would have gone mostly naked wherever climate allowed it, at least until weaving looms were invented which made clothes easier to make and more comfortable to wear.