Before Organized Civilization, humans had to fight for their survival. People banded together to find Food or hunted for it. Leaderships rose, People who were best at hunting were chosen as Leaders of a hunting group. However, many of these Groups or Tribes became enemies for many reasons.
Humans are much smaller and weaker to survive the natural environment, They had to think outside the Box. Humanity exploited their natural Intelligence, and made Tools, Weapons and Tribes. Incentivized for more food Humans captured Animals and kept them enclosed instead of hunting for them. Planting seeds and harvesting and not find fruits grow in the wild.
This Agricultural Revolution caused people to stay put, and not be as nomadic as they once were. Because of this begins a newphenomenon of claiming land and organizing cities.
What allows someone to own land? Most agreed that Land ownership can be allowed if one mixes his labor his land. In short lets say one person wants to own a Acre of land. He would have to cultivate the land and improve it for human accessibility. Because he sacrificed his time and energy, most people will agree that he is the owner of the land.
The land owner would need a objective reason, to prove to his peers around him that he is the owner of his land. This is known as the peaceful way of owning land without intruders. This process is much easier with personal products, Unlike land, products can be made. If someone made a chair, he owns that chair because he took his time to find wood and other resources to make the chair. People will respect his claim to the chair, because he has made it. If someone has bought that chair from him, people will also respect the new owner's claim, because the original creator of the chair now grants ownership to the person who bought the chair. However if in a rare instance a thief steals that chair from the owner and sells it to someone, that should not be respected by common logic. Because the thief seller did not receive the chair from the original owner.
Of course peaceful methods of land ownership was unfortunately not the only way of acquiring ownership over land.
People could just ally themselves with other people who invaded lands. Those people could not allow intruders by applying force and not by convincing others via logical reasons.
And so people have applied force to have complete authority over land. Land was worth differently, if one owns a city it is worth much more, then lets say a desert. Because due to the large amounts of people in the city, it can be used as a work force to receive and create products and resources. These products and resources can be used to make the Head or King more wealthy and enjoy more pleasurable activities. Or he could sell those products and resources for Gold which humans have understood to be very valuable, to buy rare products from far away lands. The population can also be taxed, and it can be used for drafts and recruitment for the army to invade more land.
Speaking of Gold, It is still a surprisingly good currency because of how it cannot be inflated or faked. These metals were all accepted on large amounts of lands so trading could start getting popular and make the circulation of products and resources much superior for the most part.
Cities and centralized living was both the cause and the effect of technological advancement such as superior Agriculture and Irrigation. With this population grew much faster, but as a result organizing became much more difficult. So writing was invented in Sumer, with this keeping track of crops and animals was easier and as a result made trading more efficient.
There was opposition in outside the Cities however. The Countryside would have authority over the Urban centers. Because of Industrialization not being utilized, Agriculture/Ruralism was more dominant and powerful. The Rural are naturally more Barbaric and "uncivilized", Few could read in the Cities and in the Countryside that will come close to 0. Most Ethics and Moral Traditions are from Tribal Ancestors. This Barbarism is caused by low economic standards and support for ancestral Cultural Traditions and Saying. Materialistic Possessions, Separation from nature and mass acquisition of goods is the complete opposite of the causes of a uncivilized society.
Something that can be noticed even Today, is that poverty stricken Nations seem to be unethical crude or even primitive when compared to our way of living. This is the best way to explain Ancient Society, as all knowledge was passed down from their Ancestors. They were the ones who troubled themselves to learn the hard way through trial and error to survive and pass that information down to their children, and this leading up to us. Therefore this traditional approach will be more appealing to the average person in those times, as they and their fathers were raised by those standards, Unlike the modernization growing rapidly in densely populated urban cities.