please helps i'm not American so i know nothing about its history :) How did culture spread back in early America?

The earliest civilizations developed between 4000 and 3000 BCE, when the rise of agriculture and trade allowed people to have surplus food and economic stability. Many people no longer had to practice farming, allowing a diverse array of professions and interests to flourish in a relatively confined area.

Hope it helps!!!

a countries leader should be motivated by the common good of the country.