Soon they had found that they could grow their own food if they tended the land. Then they had to get river water into the fields, and crops grew in abundance. Other tribes had saw the wealth and food the people of the river valleys had, and started raiding to take it. So to protect themselves, then they started building walls around their town. Cities grew from these towns.
I hope this helps. I am sorry if you get this wrong.
This is to give the citizens of a nation to agree or disagree with different parties's views. To make the right choice to elect their leader with the same views.
