How did egyptians change the enviroment in the red land

The ancient Egyptians thought of Egypt as being divided into two types of land, the 'black land' and the 'red land'.The 'black land' was the fertile land on the banks of the Nile. The ancient Egyptians used this land for growing their crops. This was the only land in ancient Egypt that could be farmed because a layer of rich, black silt was deposited there every year after the Nile flooded.
The 'red land' was the barren desert that protected Egypt on two sides. These deserts separated ancient Egypt from neighboring countries and invading armies. They also provided the ancient Egyptians with a source for precious metals and semi-precious stones. 

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