WORLD HISTORY

Detailed explanation-1: -The Tigris and Euphrates rivers flooded Mesopotamia at least once a year. As the floodwater receded, it left a thick bed of mud called silt. Farmers planted grain in this rich, new soil and irrigated the fields with river water.

Detailed explanation-2: -The rivers provided the people with an abundance of drinking water, and fertile soil to begin cultivation of food crops, which freed parts of their population from the dependence on food gathering and hunting.

Detailed explanation-3: -The earliest civilizations developed between 4000 and 3000 B.C.E., 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.

Detailed explanation-4: -The major four river valley civilizations were located along the Indus River, the Yellow River, the Nile River, and the Tigris and Euphrates Rivers in Mesopotamia. Although each of these was located along a river for similar reasons, they had very different political systems, religions, languages, and cultures.