Many early civilizations expanded into the large and complex types of societies in which most people still live today. They occurred in major river basins and developed where unique local climatic and soil conditions were favorable to produce agriculture. People of high status eventually used food surpluses as a way to pay for labor and to create alliances among groups. They began to trade and work in various skilled professions such as in political, religious, or military positions. Soon, large villages grew into urban centers that governed themselves and eventually empires covering vast territories. Secondary civilizations tended to develop in regions adjacent to these heartlands, or along the trade routes between them.
The earliest civilization arose in 2500 B.C.E. in a place called Sumer of what is now present-day Iraq. It grew into a powerful and prosperous region in Mesopotamia containing 500,000 people. As you can observe on the map, Mesopotamia was where the Fertile Crescent was located and it lied between the Tigris and Euphrates Rivers. People had first domesticated animals and plants in that region. Jericho was the area of a subsequent civilization because it nears the edge of the Fertile Crescent by the Mediterranean Sea. Therefore, it was the oldest known agricultural site in 8500 B.C.E. Jericho was 10 acres long and had built around it 10 ft. walls that were 30ft high. .
Trading and cultural influence shortly began to flourish in Egypt by the Nile River generating it to be the second largest ancient civilization. People settled by the Nile Valley made their living by farming since it was very fertile. The Nile River also provided an excellent trade route for Egypt with other settled civilizations such as Jericho. Subsequent civilizations also formed down along by the Red Sea and along the coastline southern Africa. .
The third greatest ancient civilization developed in the Indus Valley which is present-day Pakistan.