What are the 4 factors that led to the development of the 4 major river valley civilizations

The River Valley civilizations were built around fertile sole and they made great contributions to the world. They are:

Tigris- Euphrates valley in Mesopotamia. The Nile Valley in Egypt. The Harappan in the Indus ValleyThe Yellow river or Huang He valley in China.

The four factors they had in common were:

Religion. All civilizations had some form of religion, while the Egyptians worshiped their gods Economic Development. They focused on Agriculture creating better tools and irrigation techniques, they practiced trade and slavery. Written Language. Each civilization had their own way of writing and they used codes to write down the laws they were ruled by. Centralized Government and Class Divisions. China was ruled by an emperor, Egypt was ruled by the Pharaoh, Harappa was ruled by a king and Mesopotamia was ruled by priests.

What does that mean mon

Identify and explain two specific cultural or political influences that islamic merchants had on sub-saharan africa.