The river valleys maintained heat and protection from the earth's core.
****************************************
The silt and nutrients carried by the river would be deposited over the river's flood plain, so adding natural fertility to the soil of the valley farms. As the flat valley land is ideal for farming, so the farmers' would also add manure and fertilisers to increase crop yield.
River valleys
In the fertile river valleys.
In the fertile river valleys.
In fertile river valleys.
jhug
There are both fertile plateaus and river valleys.
A fertile river valley is a depression in the earth through which a river runs. The soil in the area of these valleys is able grow and abundance of crops.
Mountainous with fertile river valleys and coastlines.
They were in fertile, well watered river valleys.
The Tigris and Euphrates river systems, in modern-day Iraq.
River valleys provided early civilizations with fertile soil that allowed for farming.
On the plains of river valleys which were fertile and well watered.