The Sahara Desert, named after the Arabic word for desert ~ sahra, is the second largest desert in the world covering an area of some 3,630,000 square miles with sand dunes 590 feet tall, the only larger desert being in Antarctica. As large as Europe, the Sahara stretches 2,983 miles from the Red Sea to the Atlantic Ocean and 1118 miles from north to south encompassing the Western Sahara, Morocco, Mauritania, Mali, Tunisia, Algeria, Libya, Niger, Egypt, Chad, the Sudan, Somalia and Eritrea. As its reaches its southernmost limits, the Sahara becomes the Sahel, a semi-arid savannah.

Fossil formation founds in the Sahara indicate that much of the area was once wet and home to an abundance of life with animal and human remains found at over 150 sites, and the weathering of the Sphinx in Egypt, once believed to be from sandstorms, but now widely believed to be from rainfall, provides further evidence for this. However, from around 8000 to 4000 years ago the area underwent change from a landscape of grasslands and shrubs to the landscape we now see. Some identify the cause of this change being a shift in the earth's tilt from 24.14 degrees 9000 years ago to 23.45 degrees today.

Although the Sahara does receive some rainfall, it is very sporadic and some times after rain, there will be no more for years. The driest place in the Sahara Desert is in an area of Algeria known as Tidikelt, where there has now not been a drop of rain for over ten years, however, it is generally accepted that over the Sahara there is between 5 to 10 inches of rain a year compared with 24 - 33 inches for the UK per annum.

This dryness and heat (the highest temperature ever recorded being in Aziziyah, Libya 136f or 58c), make most of the Sahara uninhabitable apart from the nomads who frequent its many oases. The general population of the Sahara is believed to be around four million, however most of these live in less harsh areas on the borders of the desert in Egypt, Libya, Algeria and Mauritania. With growing desertification southwards, the desert, which has a history of expanding and shrinking, is now encroaching on communities in Niger and elsewhere promoting the idea of the Great Green Wall, a man made strip of land some nine miles wide that is to be constructed from Dakar to Eritrea across Africa, to hold back this desertification.