I do not believe there was one earth wide civilization. It is most likely technologically similar civilizations or countries like we have today. For one thing, if everyone was happy, the number of recorded wars was great according to the Bible, Vedas, Tibetan writings, and so on, including the Mayans.
If you think about it. Just like today, they are people living in "grass huts" and shepherds or nomads who do not know anything about High Technology. Perhaps they do they just want to ignore it.
Take the Amish of Pennsylvania and Ohio. They just want to ignore, not technology but electricity. They are actually very high tech and have factories with great machinery and none of it uses electricity. They use horses and carts. I have traveled and observed them during my truck driving period when I went and either picked up or delivered loads in Amish towns. Furniture mostly but sometimes grocery goods.
We see that the levels of technology differ across the earth and peoples interest in them.
Secondly, carbon dating is not all that reliable, or not linear. It is possible there could have been cataclysms from which people fled as in the one Mayan relief and then they moved and took their technology to somewhere else, which was later destroyed as well because if any of this is true and it has to be because of the ancient ruins that mankind was technologically advanced the important point is we are taught that man evolved in a linear manner and that is wrong!
Personally I do think that many of the civilizations had some independence...just like different nations and cultures of today. But I still think they were all linked to one global civilization. Based on what I've recently seen with GH and especially, this huge new megalithic site (that strangely is not mainstream news)...Gobekli Tepe in Turkey.
Yes, I have heard about that site and it is just one of the many things that is unbelievable that have no real explanation my friend @mymoontao when examined against what we are taught. The world is turning out to be very ancient and civilization goes through cycles like a Phoenix.