Across Northern Africa stretches the largest desert in the world, the Sahara, almost as large as the United States. From east to west, it measures thirty two hundred miles, farther than the distance from New York to San Francisco.

Mile after mile of scorching, shifting, sand dunes make up the Sahara, where temperatures reach 130 degrees Fahrenheit during the summer -- so hot that breathing is nearly impossible. Yet at the eastern edge of this mammoth oven lies one of the richest, most fertile valleys know to human kind -- the Nile Valley.

Flowing through the valley is the great Nile River, its four thousand one hundred and sixty miles making it the longest river in the world. It was not the river alone that make the valley so abundantly fertile. It was the fact that prior to the buildin…