Hyperborea maaaaaaan!
As hunter gatherers almost all of their time would have been spent just staying alive and safe so they had no time for the arts or writing down things for 2,000 years to remind them of what they were supposed to do. Since their life spans would have been perhaps about 30 to 35 years they simply had no time to learn stone masonry, stone carving nor building large megalithic structures. Consequently all of this complex structural and art work is simply happenstance because they were too primitive to develop high civilization.
Imagine what they might have done had they been civilized!
Indus Valley Civilization is much older but we can not read their writing.
Why is the The Mesopotamian Civilization considered the oldest civilization?
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Because with that declaration no one will pay any attention to all the blatant anomalies that predate it by thousands and even hundreds of thousands of years.
It is the steady-state that only changes ever so slowly, where everything is known - except a few minor details, ask no questions, do as you are told, and never ever look up.
Meanwhile, they’re done with nation states.
In my opinion civilization does not require writing. For example Slavic or Scandinavian states/petty kingdoms hadn't use writing until they accepted Christianity in 9-11th century AD. Nevertheless, some of them were fairly strong and well organized. Does it require cities ? I guess it depends how you define a city. It definitely requires a sort of urban permanent settlements + control over territory + the structure of power.
In short, civilization should somehow resemble contemporary era countries. Göbekli Tepe is fascinating but (unless they find out something totally new over there) it wasn't a civilization, more like a place of occasional gatherings. In the last decades we learned that people living 5-10 thousand years ago were not as primitive as previously thought but still they weren't really creating civilizations, they were more like a missing link between primitive hunters/gatherers and civilizations.
Regarding the ice age civilizations and so on... never say never but for now there's nothing indicating that they existed. They are domain of new age cults / conspiracy nutjobs, who generate a lot of fake information. Actually, many archeologists would straight away give their kidney for the opportunity to discover some unknown ancient civilization.
Jiahu is classified as a village rather than a civilization. “Civilization” implies city-sized populations, along with subsistence by agriculture, advanced social organization, and writing (rather than simply artistic symbols or pictographs).
I think it is the civilization of the Sumerians that is considered the oldest and only so by the standards of Western civilizations and only because some lineage and progression can be shown from Sumer, to the broader Middle East, down into Egypt across from the Assyrians and Hittites into the Greeks and across to the Romans and from the Greeks and Romans into all of Europe. All of that in spite of linguistics having deciphered what is called the Ind-European family of languages which includes languages of the Indian sub-continent as well as European languages with some long lost predecessors of common origin, and all while the civilizations of the Indus river valley were just as old as the Sumerians. And, no doubt there was some civilization in mainland China, along its river valleys, just as old as those that thrived in Sumer and in the Indus river valley.