Answer:
river valleys provided rich soil to grow plentiful crops
Explanation:
Both Egypt and Mesopotamia were dependent on the rivers that were in close proximity. These civilizations are in the river valleys in order to have enough water and fertile soil that produces crops for their development.
Egypt blossomed around the river on the Nile and was relying on its annual floods. Banks of the Nile river are rich in minerals that would nourish the soil during the flood, so the crops would grow enough to feed the whole culture.
The large city-states of Mesopotamia advanced quickly with the help of the rivers of Tigris and Euphrates. The land surrounding the rivers is fertile and home to various fauna species. These benefits provided cultures of Mesopotamia with the irrigation system as well as food for a living.
