River valleys provided 'rich soil' to grow plentiful crops.
<u>Explanation:</u>
In ancient Egypt and Mesopotamia, the lands adjacent to the courses of rivers were highly fertile and were called 'black land' (contrary to sandy stretches of deserts which were called 'red land').
In ancient Egypt, most settlements happened on the banks of the River Nile. The Nile valley provided with promising arable land and abundance of water.
In Mesopotamia, settlements happened on the banks of River Tigris and River Euphrates.
People settled here for there was an availability of black fertile soil which allowed them to carry out agricultural activities.
The earliest of civilizations were based around river valleys. This allowed them to irrigate fresh water to their crops allowing for better farming and therefore, bigger and better civilizations.
