Hinduism.

Disclaimer: most of this is from my mother and uncle and I haven't vetted the facts behind it.

So... many little things about Hinduism are important to this conversation. First, Hinduism is not based on any single set of ideas. It was named and labeled from "outside". So once you group those distinct people together, you have a group that disagrees on the gods behind things, but at the same time, they found a way to coexist. It wasn't quite secularism, as religion still played a role in governments and the caste system, but it was a general acceptance of the limitations of knowledge, which is what agnosticism really is.

There were atheists, polytheists, monotheists and pantheists under one umbrella, living in relative peace because one of the main tenets at the core of all the branches was the idea that we are all "delusions" of the same perfect being, living our own lives to find our own way and our own solutions to our own problems. To an atheist, the fact that someone was deluded into believing there was a god was their own struggle and they should be left to it. To a theist, the fact that someone was deluded into believing there was no god was their own struggle and they should be left to it.

Wow, did they have troubles anyway and religion ruined many things and many wars were fought, but the central tenet remained, even when it was ignored. And now most of the religious sects are continuing to ruin what could be great, but there is that one kernel of agnostic belief from thousands of years ago, that I look at my lineage and am proud of.

Some of the arguments collected on this wiki page are thousands of years old and quite interesting.

[en.wikipedia.org]

Pagan. That's not a civilization but the most benign 'belief' I could think of.

Soviet Union

Mass architecture (Pyramids, Temples, etc) generally make their appearance in the first class-stratified, city-states. And those structures are usually erected to honor the 'Gods', the priests, or the nobles. In our society, they are erected to honor banks, corporations, or television-evangelists. We've come a long way, haven't we?

Ancient people needed some explanations for what they saw, plus religion is a handy way to reinforce things that helped societies survive. Don't crap near where you eat, don't eat stuff that can kill you...lots of leviticus had real utility at the time.

The really odd thing for me is how different "morality" from religion was based on the utility of each region yet so many think THEIR morality has always been universal. It's almost like they don't think.

All Cave man groups BEFORE they started blaming everything they couldn't understand into something they needed to invent.

Before the past couple hundred years I think discretion was the better part of valor. Most agnostics and atheists were closeted. Indeed, there was no need for the word "atheist" prior to the 17th century and "agnostic" was coined early in the 20th.

I go outside everday, Wow! Nature is my Religion.

Aboriginies?

not civilizations, but tribes in central Africa had no gods for a long time and some Greeks, ie Socrates, but there were individual thinkers, not the general population

Don't know of any, but there may have been agnostic people, just like there are today? Do you know of any? Here's a link to where someone asked the question elsewhere. No one was able to come up with one: [answers.yahoo.com]

Could be these people [bbc.co.uk]