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The Sahara (الصحراء الكبرى, Aṣ-Ṣaḥrā´ al-Kubrā), the Great Desert in Arabic, is the world's largest hot desert, covering about a third of the African contient. It is the best known desert because it is so close to Europe. The legendary Sahara is not, however, the dryest. That acolade goes to South America's Atacama Desert. The Sahara is one of the hottest places on Earth with temperatures reaching 136° F (57.7° C), but it can get quite cold at night. The Sahara covers most of North Africa and creates a formidable barrier between the Arab-Berber peoples of North Africa and the Black African peoples to the south. The Sahara began to form about 4000 BC, and began driving much of the population of this formerly verdent area into the Nile Valley. Desertification is believed to be the result of shifts in the Earth's axis which increased temperatures and decreased precipitation. As a result of the climate chnge, the well watered savannah changed into the dry and very hot sandy desert know today. The same phenomenon affected the Fertile Cressent. The transition was not gradual, but occurred in two specific and abrupt episodes. The first milder event (about 4000 BC) and a second, brutal, event (about 2000 BC). [Claussen] Satellite imagery has enabled geologists to study the Sahara as never before. And one of their findings is that the Sahara is constantly changing. The Sahara regularly shrinks and expands. The Sahara's southern edge expanded into the Sahel, a dry band that separates the desert from the southern, but some reports suggest that some of these areas are green and well-watered again. The Sahara receives less than 3 inches of rain annually and some areas receive almost no rain. Some areas of the Sahara do not get any measurable rain for years at a time. There are oases in the Sahara, but cammel caravans may have to travel for days to reach one. Only these oases and camels allow traders to cross the Sahara. Crossing the desert was a major problem for traders, including slave traders, until the introduction of the camel. Archaeologists working in northern Canada have found fossils of 4 million old camels that were much larger then ones of today. It is believed that it is here that they originated and then moved to Asia across the northern land bridge. Millions of years ago the north was a bit warmer then now. The same shift of the Earth's axis that turned much of North Africa to desert also turned the far north to an icecap.
The Sahara (الصحراء الكبرى, Aṣ-Ṣaḥrā´ al-Kubrā), the Great Desert in Arabic, is the world's largest hot desert, covering about a third of the African contient. It is the best known desert because it is so close to Europe. The legendary Sahara is not, however, the dryest. That acolade goes to South America's Atacama Desert. The Sahara is one of the hottest places on Earth with temperatures reaching 136° F (57.7° C), but it can get quite cold at night.
The Sahara receives less than 3 inches of rain annually and some areas receive almost no rain. Some areas of the Sahara do not get any measurable rain for years at a time.
The Sahara covers most of North Africa and creates a formidable barrier between the Arab-Berber peoples of North Africa and the Black African peoples to the south.
The Sahara began to form about 4000 BC, and began driving much of the population of this formerly verdent area into the Nile Valley. Desertification is believed to be the result of shifts in the Earth's axis which increased temperatures and decreased precipitation. As a result of the climate chnge, the well watered savannah changed into the dry and very hot sandy desert know today. The same phenomenon affected the Fertile Cressent. The transition was not gradual, but occurred in two specific and abrupt episodes. The first milder event (about 4000 BC) and a second, brutal, event (about 2000 BC). [Claussen] Satellite imagery has enabled geologists to study the Sahara as never before. And one of their findings is that the Sahara is constantly changing. The Sahara regularly shrinks and expands.
The Sahara's southern edge expanded into the Sahel, a dry band that separates the desert from the southern, but some reports suggest that some of these areas are green and well-watered again.
An oasis is an isolated area where water appears to support vegetation surromded by desert. Oases are formed by underground rivers or aquifers where water can reach the surface even in vast desert areas. This is done by natural pressure or by man made wells. Substrata of impermeable rock can trap large volumes of water and retain it in vast pockets. Other structures like long faulting subsurface ridges or volcanic dikes water can collect water which percolate to the surface. Before the arrival of man, desert oasis were found by migrating birds who through their dropping deposit seeds allowing natural vegetation to develop. Sometimes there is only enough water to to sustain a small well. In other cases a small area of land can be irrigated to support a limited population. The location of these oases has been of vital importance for trade across the Sahara and other desert areas. Before the appearance of the camel, oasis were not common enough or close enough to allow trade to flow. As a result, the primary conduit for Sub-Saharan trade to reach Europe and the Middle East was the Nile. There are oases in the Sahara, but before the cammel caravans could not reach the scattered oasis, caravans had to travel for days to reach the scattered oasis.
This changed with the introduction of the camel. The camel gave traders the capability of crossing vast tracts of desert by connecting the widely dispersed Sahran oasis. It is no accident that the great sub-Saharan African empires began to form after the camel made possible the development of trans-Sharan trade routes centerd around the desert oasis. Caravans must transit the Sahara via the oases so that neededsupplies of water and food can be replenished. Camels can travel long distances without water, but they need water like any animal. And of course humnan exhaust the awter carried by camels. Thus control of a desert oasis meant control of trade routes which was of vast econimic and political importance.
Crossing the desert was a major problem for traders, including slave traders, until the introduction of the camel. Archaeologists working in northern Canada have found fossils of 4 million old camels that were much larger then ones of today. It is believed that it is here that they originated and then moved to Asia across the northern land bridge. Millions of years ago the north was a bit warmer then now. The same shift of the Earth's axis that turned much of North Africa to desert also turned the far north to an icecap. The Camel first appeared in North America. From North America they spread west across the Bearing Sea land bridge to East Asia and south into South America. The South Amerian caneloids became llamas and their more exotic related species, alpacas, and vicuñas. It is the western migration that developed into modern camels. The camels in East Asia gradually spread further west to Central Asia and Iran and Arabia. (and also south to South America where they became llamas and vicunas and alpacas). The camels in North Americawent extincr, probably during the Ice Age. They survived in Asia and were eventually brought to North Africa as domesticated animal. It was people in Central Asia who first domesticate camels. Camels had the ability to carry goods over long distances with little water. They proved very useful in crossing the Gobi Desert of Central Asia and it was here that they were first domesticated. This occured long after other livestock animals (cows, sheep, and pigs) were domsticated. Archeologists believe that this occurred about the same time horses from Central Asia were domesticated (3000 BC). Camels are not as tame as the earlier domesticated livestock animals. Camels were introduced to North Africa by Arab traders gradually moving west.
The Sahara is a big black hole in most histories who focus on the fascinating civilizations north of the Sahara. In fact a great deal of facinating history has taken place not only north of the Sahara, but both within and south of the Sahara. Thus it is interesting to discuss the history of the region with a focus on the Sahara. We do not yet fully understand the history, especially the early history, but we have begun to build a history of the Sahara. The history of Africa was findamentally affected by the Sahara. As the Sahara developed in created a barrier thg it was virtually impossible to cross, blocking migrtion and commerce. Once the desert develope the only imprtant way to cross the Sahara was the Nile Valley in the East. The Phoenicians traded along the Atlantic coast, but to a very limited extent. Only the introduction of the cammel enabled man to cross the Shara (3rd century AD). Gold, salt, and slaves were impprtant coomodities. It also led to the fevelopment of the great African empires beginning wih Ghana.
There was much more activity along the Indian Ocean coast of East Africa, orimarilt after the Aslamic explosion (8th century AD). This was the beginning of the African slave trade in sybstantial numbers. Slaves have been briught north over the Sahara in cammel caravans, but the numbers were limited. The Arab Indian Ocan slave trade ivolved far greater bnumbers of captive people. Cannel cravans remained the only way of crossing gthe Sahara until the invention of the autombile (20th century). Much of the Sahara was controlled by France until after World War II. France like other European colonial powers began granting independence to theeir colonies. The nakor exception was Algerain awhere a brutal colonial war ws fought. Ghe Algerian war for independence was the turning point for the French Empire. In recent yeras, Interestingly, developments in the Sahara have begun to appear in the media. The first such major issue was the Sudanese Arab genocide of African peoples in Darfur. This freceived much more coverage than the longer term assault on the largely Christian African people of people of southern Sudan which eventually led to independence. Then there was an Islamist assult on oil workers in southern Algeria (2013) and the related Islamist effort to seize cointrol of Mali. And then the French intervention in the Central African Republic where an Islamist rebel force seize control of a largely Christian nation. All this taking place in a Saharan amd Sahelian region racked by expanding disertification as well as increasing mineral finds. Today, Islamic fundamentalism is a major problem in the area.
Fage, J.D. A History of Africa (Routledge, 4th edition, 2001).
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