Sahara
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[[Image:Sahara satellite hires.jpg|thumb|right|Satellite image]]
[[Image:Libya 5101 Fozzigiaren Arch Tadrart Acacus Luca Galuzzi 2007.jpg|thumb|A natural rock arch in south western Libya]]
[[Image:Sahara1.JPG|thumb|right|The Sahara in [[Algeria]].]]
The '''Sahara''' ({{lang-ar|الصحراء الكبرى}}, ''{{Unicode|aṣ-ṣaḥrā´ al-koubra}}'', "The Great Desert") is the world's largest hot [[desert]] and the world's second largest desert after [[Antarctica]] <ref>Since there is little precipitation in Antarctica as well, except at the coasts, the interior of the continent is technically the largest desert in the world.</ref>. At over 9,000,000 [[square kilometre]]s (3,500,000 [[square mile|sq mi]]), it covers most parts of [[Northern Africa]]; an area stretching from the [[Red Sea]], including parts of the [[Mediterranean]] coasts, to the outskirts of the [[Atlantic Ocean]]. To the south, it is delimited by the [[Sahel]], a belt of [[Tropical and subtropical grasslands, savannas, and shrublands|semi-arid tropical savanna]] separating the Sahara from [[Sub-Saharan Africa]].
The Sahara is almost as large as the continental [[United States]], and is larger than [[Australia]]. The Sahara has an intermittent history that may go back as much as 3 million years.<ref>MIT OpenCourseWare. (2005) "[http://ocw.mit.edu/NR/rdonlyres/Earth--Atmospheric--and-Planetary-Sciences/12-453Fall-2005/882ACC1A-608F-41EF-97E2-B7616F37D425/0/1_lecture1_1.pdf 9-10 thousand Years of African Geology]". Massachusetts Institute of Technology. Pages 6 and 13</ref> Some of the sand dunes can reach 180 meters (600 feet) in height.<ref>Arthur N. Strahler and Alan H. Strahler. (1987) Modern Physical Geography–Third Edition. New York: John Wiley & Sons. Page 347</ref> Its name comes from the Tamajaq [[Tuareg]] language word [[Tenere]], which means the desert, translated into the Arabic it gave Sahara "desert": (صَحراء), "ṣaḥrā´" ({{Audio|ar-Sahara.ogg|صحراء}}).<ref>[http://www.etymonline.com/index.php?term=Sahara "Sahara."] ''[[Online Etymology Dictionary]].'' Douglas Harper, Historian. Accessed on [[June 25]], [[2007]].</ref><ref>[http://online.ectaco.co.uk/main.jsp?do=e-services-dictionaries-word_translate1&status=translate&lang1=23&lang2=ar&source_id=2119140 English-Arabic online dictionary]</ref>
But the original name of the Sahara is: [[Tinariwen]] (the deserts), as for the indigenous people of the Sahara, the Tuareg people, the Sahara is not a desert, but many deserts, distinct and different in nature and landscapes.
==Overview==
[[Image:SafsafOasis SAR comparison.jpg|thumb|The top image shows the [[Safsaf Oasis]] on the surface of the Sahara. The bottom (using [[radar]]) is the rock layer underneath, revealing black channels cut by the meandering of an ancient river that once fed the oasis.]]
The boundaries of the Sahara are the [[Atlantic Ocean]] on the west, the [[Atlas Mountains]] and the [[Mediterranean Sea]] on the north, the [[Red Sea]] and [[Egypt]] on the east, and the [[Sudan (region)|Sudan]] and the valley of the [[Niger River]] on the south. The Sahara is divided into western Sahara, the central [[Ahaggar Mountains]], the [[Tibesti Mountains]], the [[Aïr Mountains]] (a region of desert mountains and high plateaus), [[Tenere]] desert and the [[Libyan desert]] (the most arid region). The highest peak in the Sahara is [[Emi Koussi]] (3415 [[metre|m]]) in the [[Tibesti Mountains]] in northern [[Chad]].
The Sahara divides the [[continent]] of [[Africa]] into [[North Africa|North]] and [[Sub-Saharan Africa]]. The southern border of the Sahara is marked by a band of semiarid [[savanna]] called the [[Sahel]]; south of the Sahel lies the lusher Sudan and the [[Congo River Basin]]. Most of the Sahara consists of rocky [[hamada]]; [[erg (landform)|ergs]] (large sand [[dune]]s) form only a minor part.
People lived on the edge of the desert thousands of years ago<ref name="Post-Ice Age Sahara">[http://discover.com/issues/oct-06/rd/sahara-desert-savanna-climate/ Discover Magazine], 2006-Oct.</ref> since, immediately after the last [[ice age]], the Sahara was a much wetter place than it is today. Over 30,000 [[petroglyph]]s of river animals such as [[crocodile]]s (which still exist in parts of the desert)<ref name=Crocodiles>[http://news.nationalgeographic.com/news/2002/06/0617_020618_croc.html National Geographic News], 2006-06-17.</ref> survive, with half found in the [[Tassili n'Ajjer]] in southeast [[Algeria]]. [[Fossil]]s of [[dinosaur]]s, including ''[[Afrovenator]]'', ''[[Jobaria]]'' and ''[[Ouranosaurus]]'', have also been found here. The modern Sahara, though, is not as lush in vegetation, except in the [[Nile]] Valley, at a few [[oasis|oases]], and in the northern highlands, where Mediterranean plants such as the [[olive]] tree are found to grow. The region has been this way since about 3000 BC. Some 2.5 million people live in the Sahara, most of these in Egypt, [[Mauritania]], [[Morocco]] and [[Algeria]]. Dominant ethnicities in the Sahara are various [[Berber people|Berber]] groups including [[Tuareg]] tribes, various [[Arab]]ised Berber groups such as the [[Hassaniya]]-speaking Maure ([[Moors]], also known as [[Sahrawis]]), and various "black African" ethnicities including [[Tubu]], [[Nubians]], [[Zaghawa]], [[Kanuri]], [[Fula people|Peul]] (Fulani), [[Hausa]] and [[Songhai]]. Important cities located in the Sahara include [[Nouakchott]], the capital of Mauritania; [[Tamanrasset]], [[Ouargla]], [[Bechar]], [[Hassi Messaoud]], [[Ghardaia]], [[El Oued]], Algeria; [[Timbuktu]], [[Mali]]; [[Agadez]], [[Niger]]; [[Ghat]], Libya; and [[Faya-Largeau]], [[Chad]].
It has been reported that the Sahara is expanding south by as much as 30 miles per year, overwhelming degraded grasslands,<ref name="Sahara Expanding">[http://timesofindia.indiatimes.com/articleshow/1859784.cms Sahara Expanding, accessed on April 20, 2008]</ref> <ref name="Sahara">[http://www.calacademy.org/exhibits/africa/exhibit/sahara/ Sahara, accessed on April 20, 2008]</ref> taking over the [[Sahel]], the dry tropical [[savanna]] that has defined the Sahara's southern limit. [[Global warming]] and poor farming methods have been given as possible causes.<ref name="Hunger is spreading in Africa">http://www.csmonitor.com/2005/0801/p01s02-woaf.html Hunger is spreading in Africa, accessed on April 20, 2008</ref> The spreading of deserts is known as "[[desertification]]," and the phenomenon is occurring in other desert areas worldwide.
==Geography==
[[Image:Africa satellite orthographic.jpg|thumb|249px|A geographical map of Africa, showing the ecological break that defines the Saharan area]]
The Sahara covers huge parts of [[Algeria]], [[Chad]], [[Egypt]], [[Libya]], [[Mali]], [[Mauritania]], [[Morocco]], [[Niger]], [[Western Sahara]], [[Sudan]] and [[Tunisia]]. It is one of three distinct physiographic provinces of the [[Physiographic_regions_of_the_world#Compendium_table_of_the_worlds_physiographic_regions|African massive physiographic division]].
The desert landforms of the Sahara are shaped by wind ([[eolian]]) or by occasional rains, and include sand dunes and dune fields or sand seas ([[erg (landform)|erg]]), stone plateaus ''([[hamada]])'', gravel plains ''(reg)'', dry valleys ''([[wadi]])'', and [[salt flat]]s ''(shatt'' or ''chott)''.<ref>"Sahara desert" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1327_full.html]. Accessed December 30, 2007.</ref> Unusual landforms include the [[Richat Structure]] in Mauritania.
Several deeply dissected mountains and mountain ranges, many volcanic, rise from the desert, including the [[Aïr Mountains]], [[Ahaggar Mountains]], [[Saharan Atlas]], [[Tibesti Mountains]], [[Adrar des Iforas]], and [[Red Sea Hills]]. The highest peak in the Sahara is [[Emi Koussi]], a [[shield volcano]] in the [[Tibesti]] range of northern Chad.
Most of the rivers and streams in the Sahara are seasonal or intermittent, the chief exception being the [[Nile River]], which crosses the desert from its origins in central Africa to empty into the Mediterranean. Underground [[aquifer]]s sometimes reach the surface, forming [[oasis|oases]], including the [[Bahariya Oasis|Bahariya]], [[Ghardaïa]], [[Timimoun]], [[Kufrah Oasis|Kufrah]], and [[Siwah Oasis|Siwah]].
The center of the Sahara is hyper-arid, with little vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and desert shrub, with trees and taller shrubs in wadis where moisture collects.
To the north, the Sahara reaches to the Mediterranean Sea in [[Egypt]] and portions of [[Libya]], but in [[Cyrenaica]] and the [[Magreb]], the Sahara borders [[Mediterranean forest, woodland, and shrub]] ecoregions of northern Africa, which have a [[Mediterranean climate]] characterized by a winter rainy season. According to the [[botanic]]al criteria of Frank White<ref>Wickens, Gerald E. (1998) ''Ecophysiology of Economic Plants in Arid and Semi-Arid Lands''. Springer, Berlin. ISBN 978-3-540-52171-6</ref> and geographer [[Robert Capot-Rey]],<ref name=Grove1958>{{cite journal
| author = Grove, A.T., nicole
| year = 1958,2007
| title = The Ancient Erg of Hausaland, and Similar Formations on the South Side of the Sahara
| journal = The Geographical Journal
| volume = 124
| issue = 4
| pages = 528–533
| issn =
| doi =
| url = http://links.jstor.org/sici?sici=0016-7398(195812)124%3A4%3C528%3ATAEOHA%3E2.0.CO%3B2-3
| accessdate = 2007-05-23
}}</ref><ref name=Bisson2003>{{cite book
| author = Bisson, J.
| year = 2003
| title = Mythes et réalités d'un désert convoité: le Sahara
| publisher = L'Harmattan
| isbn =
}}{{fr icon}}</ref> the northern limit of the Sahara corresponds to the northern limit of [[Date Palm]] cultivation ''(Phoenix dactylifera)'', and the southern limit of [[Esparto]] ''(Stipa tenacissima)'', a grass typical of the Mediterranean climate portion of the Maghreb and Iberia. The northern limit also corresponds to the 100 mm [[Contour line#Temperature and related subjects|isohyet]] of annual precipitation.<ref name=Walton2007>{{cite book
| author = Walton, K.
| year = 2007
| title = The Arid Zones
| publisher = Aldine
| isbn =
}}</ref>
To the south, the Sahara is bounded by the [[Sahel]], a belt of dry [[Tropical and subtropical grasslands, savannas, and shrublands|tropical savanna]] with a summer rainy season that extends across Africa from east to west. The southern limit of the Sahara is indicated botanically by the southern limit of ''[[Cornulaca monacantha]]'' (a [[Chenopodiaceae]]), or northern limit of the ''[[Cenchrus biflorus]]'', a [[Poaceae|grass]] typical of the [[Sahel]].<ref name=Grove1958>{{cite journal
| author = Grove, A.T., nicole
| year = 1958,2007
| title = The Ancient Erg of Hausaland, and Similar Formations on the South Side of the Sahara
| journal = The Geographical Journal
| volume = 124
| issue = 4
| pages = 528–533
| issn =
| doi =
| url = http://links.jstor.org/sici?sici=0016-7398(195812)124%3A4%3C528%3ATAEOHA%3E2.0.CO%3B2-3
| accessdate = 2007-05-23
}}</ref><ref name=Bisson2003>{{cite book
| author = Bisson, J.
| year = 2003
| title = Mythes et réalités d'un désert convoité: le Sahara
| publisher = L'Harmattan
| isbn =
}}{{fr icon}}</ref> According to [[climate|climatic]] criteria, the southern limit of the Sahara corresponds to the 150 mm isohyet of annual precipitation (keeping in mind that [[Precipitation (meteorology)|precipitation]] varies strongly from one year to another).<ref name=Walton2007>{{cite book
| author = Walton, K.
| year = 2007
| title = The Arid Zones
| publisher = Aldine
| isbn =
}}</ref>
==Climate history==
[[Image:Hoggar8.jpg|thumb|right|An [[oasis]] in the [[Ahaggar Mountains]]]]
The climate of the Sahara has undergone enormous variation between wet and dry over the last few hundred thousand years.<ref name="Lakes"> {{Citation | title=Ancient Lakes of the Sahara | publisher=American Scientist | volume=94 | year=2006 | pages= pp.58–65 | author=Kevin White and David J. Mattingly | number=1}} </ref> During the last [[ice age]], the Sahara was bigger than it is today, extending south beyond its current boundaries.<ref>Christopher Ehret. ''The Civilizations of Africa.'' University Press of Virginia, 2002.</ref> The end of the ice age brought better times to the Sahara, from about 8000 BC to 6000 BC, perhaps due to [[low pressure area]]s over the collapsing [[ice sheet]]s to the north.<ref>[http://www.cru.uea.ac.uk/~e118/Fezzan/fezzan_palaeoclim.html Fezzan Project — Palaeoclimate and environment], retrieved [[March 15]], [[2006]].</ref>
Once the ice sheets were gone, the northern part of the Sahara dried out. However, not long after the end of the ice sheets, the [[monsoon]], which currently brings [[rain]] only as far as the Sahel, came further north and counteracted the drying trend in the southern Sahara. The monsoon in Africa (and elsewhere) is due to heating during the summer. Air over land becomes warmer and rises, pulling in cool wet air from the ocean, which causes rain. Paradoxically, the Sahara was wetter when it received more solar [[insolation]] in the summer. Changes in solar insolation are caused by changes in the Earth's [[orbital elements|orbital parameters]] (9,000 years ago the Earth's axis had a stronger tilt than it does presently, and [[Apsis|perihelion]] occurred at the end of July).<ref>"Geophysical Research Letters" [http://www.awi.de/fileadmin/user_upload/Research/Research_Divisions/Climate_Sciences/Paleoclimate_Dynamics/Modelling/Research_periods/SimulationAbrupt.pdf Simulation of an abrupt change in Saharan vegetation in the mid-Holocene] - July 15th, 1999</ref>
By around 3400 BC, the monsoon retreated south to approximately where it is today,<ref name = "Science Daily">[http://www.sciencedaily.com/releases/1999/07/990712080500.htm Sahara's Abrupt Desertification Started by Changes in Earth's Orbit], Accelerated by Atmospheric and Vegetation Feedbacks.</ref> leading to the gradual rather than abrupt [[desertification]] of the Sahara.<ref>{{ cite journal | last = Kröpelin | first = Stefan | authorlink = | coauthors = ''et al.'' | year = 2008 | month = | title = Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years | journal = Science | volume = 320 | issue = 5877 | pages = 765–768 | doi = 10.1126/science.1154913 | url = | accessdate = | quote =| pmid = 18467583 }}</ref> The Sahara is currently as dry as it was about 13,000 years ago.<ref name=Lakes /> These conditions are responsible for what has been called the [[Sahara Pump Theory]].
The Sahara has one of the harshest climates in the world. The prevailing north-easterly wind often causes the sand to form [[dust storm|sand storms]] and [[dust devil]]s.<ref>[http://www.oxfam.org.uk/coolplanet/ontheline/explore/nature/deserts/sahara.htm Oxfam Cool Planet - the Sahara] - access [[February 10]], [[2008]]</ref> Precipitation, while rare, is not unknown. Half of the Sahara receives less than 2 [[Centimetre|cm]] of rain a year, with the rest receiving up to 10 cm a year.<ref>[http://www.cru.uea.ac.uk/tiempo/newswatch/feature060915.htm Tiempo Climate Newswatch: Climate Change and the Sahara]</ref> The rainfall happens very rarely, but when it does it is usually torrential when it occurs after long dry periods, which can last for years.
Presently, the climate is changing, and the Sahara is supposedly expanding southward by about 30 miles per year (according to loose unsourced references in the popular press <ref>[http://www.csmonitor.com/2005/0801/p01s02-woaf.html]</ref>).
==Ecoregions==
The Sahara comprises several distinct [[ecoregion]]s, whose variations in temperature, rainfall, elevation, and soils harbor distinct communities of plants and animals. According to the [[Worldwide Fund for Nature]] (WWF), the ecoregions of the Sahara include:
* [[Atlantic coastal desert]]: The coastal desert occupies a narrow strip along the [[Atlantic Ocean|Atlantic]] coast, where fog generated offshore by the cool [[Canary Current]] provides sufficient moisture to sustain a variety of [[lichen]]s, [[succulent plant|succulents]], and shrubs. It covers 39,900 square kilometers (15,400 square miles) in [[Western Sahara]] and [[Mauritania]].<ref>"Atlantic coastal desert" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1304_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[North Saharan steppe and woodlands]]: This ecoregion lies along the northern edge of the desert, next to the [[Mediterranean forests, woodlands, and shrub]] ecoregions of the northern [[Maghreb]] and [[Cyrenaica]]. Winter rains sustain shrublands and dry woodlands that form a transition between the [[Mediterranean climate]] regions to the north and the hyper-arid Sahara proper to the south. It covers 1,675,300 square kilometers (646,800 square miles) in [[Algeria]], [[Egypt]], [[Libya]], Mauritania, [[Morocco]], [[Tunisia]], and Western Sahara.<ref>"North Saharan steppe and woodlands" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1321_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[Sahara Desert (ecoregion)|Sahara desert]]: This ecoregion covers the hyper-arid central portion of the Sahara where rainfall is minimal and sporadic. Vegetation is rare, and this ecoregion consists mostly of sand dunes ''(erg, chech, raoui)'', stone plateaus ''(hamadas)'', gravel plains ''(reg)'', dry valleys ''(wadis)'', and salt flats. It covers 4,639,900 square kilometers (1,791,500 square miles) of Algeria, [[Chad]], Egypt, Libya, [[Mali]], Mauritania, [[Niger]], and [[Sudan]].<ref>"Sahara desert" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1327_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[South Saharan steppe and woodlands]]: The South Saharan steppe and woodlands occupy a narrow band running east and west between the hyper-arid Sahara and the [[Sahel]] savannas to the south. Movements of the equatorial [[Intertropical Convergence Zone]] (ITCZ) bring summer rains during July and August which average 100 to 200 mm, but vary greatly from year to year. These rains sustain summer pastures of grasses and herbs, with dry woodlands and shrublands along seasonal watercourses. The ecoregion covers 1,101,700 square kilometers (425,400 square miles) in Algeria, Chad, Mali, Mauritania, and Sudan.<ref>"South Saharan steppe and woodlands" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1329_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[West Saharan montane xeric woodlands]]: Several volcanic highlands in the western portion of the Sahara provide a cooler, moister environment that supports Saharo-Mediterranean woodlands and shrublands. The ecoregion covers 258,100 square kilometers (99,700 square miles), mostly in the [[Tassili-n-Ajjer]] of Algeria, with smaller enclaves in the [[Aïr]] of Niger, the [[Dhar Adrar]] of Mauritania, and the [[Adrar des Iforas]] of Mali and Algeria.<ref>"West Saharan montane xeric woodlands" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1332_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[Tibesti-Jebel Uweinat montane xeric woodlands]]: The [[Tibesti]] and [[Jebel Uweinat]] highlands foster higher, more regular rainfall and cooler temperatures, which support woodlands and shrublands of [[Date Palm|palm]]s, [[acacia]]s, [[myrtle]], [[oleander]], [[Tamarix]], and several rare and endemic plants. The ecoregion covers 82,200 square kilometers (31,700 square miles) in the Tibesti of Chad and Libya, and Jebel Uweinat on the border of Egypt, Libya, and Sudan.<ref>"Tibesti-Jebel Uweinat montane xeric woodlands" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1331_full.html]. Accessed [[December 29]], [[2007]].</ref>
* [[Saharan halopytics]]: Seasonally-flooded saline depressions in the Sahara are home to [[halophytic]], or salt-adapted, plant communities. The Saharan halophytics cover 54,000 square kilometers (20,800 square miles), including the [[Qattara Depression|Qattara]] and [[Siwa Depression|Siwa]] depressions in northern Egypt, the [[Tunisian salt lakes]] of central Tunisia, [[Chott Melghir]] in Algeria, and smaller areas of Algeria, Mauritania, and Western Sahara.<ref>"Saharan halophytics" WWF Scientific Report [http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa0905_full.html]. Accessed [[December 29]], [[2007]].</ref>.
==Fauna==
[[Image:Tunisia Sahara.jpg|thumb|Sahara desert in Tunisia and shadows of camels with travelers]]
* [[Dromedary|Dromedary camels]] and [[goat]]s are the most domesticated animals found in the Sahara. Because of its qualities of sobriety, endurance and speed, the dromedary is the favorite animal used by [[nomad]]s.
* The [[Leiurus quinquestriatus]] (aka Deathstalker) scorpion which can be 10 cm long. Its [[Agitoxin]] and [[Scyllatoxin]], toxins contained within the venom, are fatal in the majority of cases.
* The [[monitor lizard]]. It has been suggested that the occasional habit of varanids to stand on their two hind legs and to appear to "monitor" their surroundings led to the original Arabic name ''waral'' ورل, which is translated to English as "monitor".<ref>Pianka, E.R.; King, D.R. and King, R.A. 2004. ''Varanoid Lizards of the World''. Indiana University Press.</ref>
* [[Cerastes (genus)|Sand vipers]], which average less than 50 cm in length. Many have a pair of horns, one over each eye. Active at night, they usually lie buried in the sand with only their eyes visible. Bites are painful, but rarely fatal.
* The [[fennec]], an [[omnivore]].
* The [[hyrax]]. It first appears in the [[fossil]] record over 40 million years ago, and for many millions of years hyraxes were the primary terrestrial herbivore in Africa.
* The [[ostrich]] which is a [[flightless bird]] native to Africa. They became rare because they have been driven out.
* The [[addax]], a large white [[antelope]], is a threatened species. Adapted to the desert, they can remain months without drinking, even a whole year.
* The Saharan [[cheetah]] lives in [[Niger]], [[Mali]] and [[Chad]]. There remain only a few hundred cheetahs which are very cautious, avoiding any human presence, the cheetah flees the sun from April to October. It then seeks the shelter of shrubs such as balanites and acacias. They are unusually pale.{{Fact|date=July 2007}} <!-- No indication of this variety in the Cheetah article -->
There exist other animals in the Sahara (birds in particular) such as [[African Silverbill]] and [[Black-throated Firefinch]] among others.
==History==<!-- This section is linked from [[Civilization]] -->
[[Image:Saraha-1908.png|thumb|left|Photo of the Sahara from 1908]]
===Egyptians===
By 6000 BC [[predynastic Egypt]]ians in the southwestern corner of Egypt were [[herding]] cattle and [[construction|constructing]] large buildings. Subsistence in organized and permanent [[town|settlement]]s in predynastic Egypt by the middle of the 6th millennium BC centered predominantly on [[cereal]] and animal [[History of agriculture|agriculture]]: [[cattle]], [[goat]]s, [[pig]]s and [[sheep]]. [[Metal]] objects replaced prior ones of [[rock (geology)|stone]]. [[Tanning]] of animal skins, [[pottery]] and [[weaving]] are commonplace in this era also.<ref name= Predynastic> Predynastic] (5,500–3,100 BC), Tour Egypt].</ref> There are indications of seasonal or only temporary occupation of the [[Al Fayyum]] in the 6th millennium BC, with food activities centering on [[fishing]], [[hunting]] and food-gathering. Stone [[arrowhead]]s, [[knife|knives]] and [[scraper]]s are common.<ref name= Fayum>[http://www.digitalegypt.ucl.ac.uk/fayum/fayumb.html Fayum, Qarunian] (Fayum B, about 6000–5000 BC?), [http://www.digitalegypt.ucl.ac.uk Digital Egypt].</ref> [[Burial]] items include pottery, [[jewelry]], farming and hunting equipment, and assorted foods including dried meat and fruit. The dead are buried facing due west.<ref name=Predynastic/>
By 3400 BC, the Sahara was as dry as it is today, and it became a largely impenetrable barrier to humans, with only scattered settlements around the oases, but little [[trade]] or commerce through the desert. The one major exception was the [[Nile|Nile Valley]]. The Nile, however, was impassable at several [[Cataracts of the Nile|cataract]]s, making trade and contact by boat difficult.
===Nubians===
During the [[Neolithic]], before the onset of desertification, the central Sudan had been a rich environment supporting a large population ranging across what is now barren desert, like the Wadi el-Qa'ab. By the 5th millennium BC, the peoples who inhabited what is now called [[Nubia]], were full participants in the "agricultural revolution," living a settled lifestyle with domesticated plants and animals. Saharan rock art of cattle and herdsmen found suggests the presence of a cattle cult like those found in [[Sudan]] and other pastoral societies in Africa today.<ref>[http://www.anth.ucsb.edu/faculty/stsmith/research/nubia_history.html History of Nubia]</ref> Megaliths found at [[Nabta Playa]] are overt examples of probably the world's first known [[Archaeoastronomy]] devices, predating [[Stonehenge]] by some 1000 years.<ref>[http://www.planetquest.org/learn/nabta.html PlanetQuest: The History of Astronomy] - Retrieved on 2007-08-29</ref> This complexity, as observed at Nabta Playa, and as expressed by different levels of authority within the society there, likely formed the basis for the structure of both the Neolithic society at Nabta and the Old Kingdom of Egypt.<ref>[http://www.comp-archaeology.org/WendorfSAA98.html Late Neolithic megalithic structures at Nabta Playa] - by Fred Wendorf (1998)</ref>
===Phoenicians===
[[Image:Sahara Desert Tribal Camp.jpg|thumb|right|A Saharan village in [[Mali]]]]
The peoples of [[Phoenicia]], who flourished between 1200-800 BC, created a confederation of kingdoms across the entire Sahara to Egypt. They generally settled along the Mediterranean coast, as well as the Sahara, among the peoples of [[Ancient Libya]], who were the ancestors of peoples who speak [[Berber languages]] in North Africa and the Sahara today, including the [[Tuareg]] of the central Sahara.
The Phoenician alphabet seems to have been adopted by the ancient Libyans of north Africa, and [[Tifinagh]] is still used today by Berber-speaking Tuareg camel herders of the central Sahara.
Sometime between 633 BC and 530 BC, [[Hanno the Navigator]] either established or reinforced Phoenician colonies in [[Western Sahara]], but all ancient remains have vanished with virtually no trace. (See [[History of Western Sahara]].)
===Greeks===
By 500 BC, a new influence arrived in the form of the [[Ancient Greece|Greeks]]. Greek traders spread along the eastern coast of the desert, establishing trading colonies along the [[Red Sea]] coast. The [[Carthage|Carthaginians]] explored the Atlantic coast of the desert. The turbulence of the waters and the lack of markets never led to an extensive presence further south than modern [[Morocco]]. Centralized states thus surrounded the desert on the north and east; it remained outside of the control of these states. Raids from the [[nomad]]ic [[Berber people]] of the desert were a constant concern of those living on the edge of the desert.
[[Image:Burnus sulla spalla.jpg|thumb|An [[Algeria]]n man in urban dress]]
===Urban civilization===
An urban civilization, the [[Garamantes]], arose around this time in the heart of the Sahara, in a valley that is now called the [[Wadi al-Ajal]] in [[Fazzan]], [[Libya]].<ref name="Lakes" /> The Garamantes achieved this development by digging tunnels far into the mountains flanking the valley to tap [[fossil water]] and bring it to their fields. The Garamantes grew populous and strong, conquering their neighbors and capturing many slaves (which were put to work extending the tunnels). The ancient Greeks and the [[Ancient Rome|Romans]] knew of the Garamantes and regarded them as uncivilized nomads. However, they traded with the Garamantes, and a [[Roman bath]] has been found in the Garamantes capital of Garama. [[Archaeology|Archaeologists]] have found eight major towns and many other important settlements in the Garamantes territory. The Garamantes civilization eventually collapsed after they had depleted available water in the [[aquifer]]s, and could no longer sustain the effort to extend the tunnels still further into the mountains.<ref name = "Keys">Keys, David. 2004. Kingdom of the Sands. ''Archaeology''. Volume 57 Number 2, March/April 2004. [http://www.archaeology.org/0403/abstracts/sands.html Abstract] retrieved [[March 13]], [[2006]].</ref>
===Trans-Saharan trade===
{{Main|Trans-Saharan trade}}
[[Image:Benjamin of Tudela.jpg|thumb|right|The 12th Century traveller [[Benjamin of Tudela]] in the Sahara (Dumouza, 19th Century engraving)]]
Following the [[Islamic]] conquest of North Africa in the seventh century [[Common Era|CE]], trade across the desert intensified. The kingdoms of the [[Sahel]], especially the [[Ghana Empire]] and the later [[Mali Empire]], grew rich and powerful exporting [[gold]] and [[salt]] to North Africa. The emirates along the [[Mediterranean Sea]] sent south manufactured goods and [[horse]]s. From the Sahara itself, [[edible salt|salt]] was exported. This process turned the scattered [[oasis]] communities into trading centres, and brought them under the control of the empires on the edge of the desert. A significant slave trade crossed the desert (See [[Arab slave trade]]).
This trade persisted for several centuries until the development in Europe of the [[caravel]] allowed ships, first from [[Portugal]] but soon from all Western Europe, to sail around the desert and gather the resources from the source in [[Guinea (region)|Guinea]]. The Sahara was rapidly remarginalized.
===European imperialism===
At the beginning of the 19th century, most of the northern Sahara, including most of present-day [[Algeria]], [[Tunisia]], [[Libya]], and [[Egypt]], was part of the [[Ottoman Empire]]. The Sahel and southern Sahara were home to several independent states.
European colonialism in the Sahara began in the 19th century. [[France]] conquered Algeria from the Ottomans in 1830, and French rule spread south from Algeria and eastwards from [[Senegal]] into the upper [[Niger River|Niger]] to include present-day [[Algeria]], [[Chad]], [[Mali]], [[Mauritania]], [[Morocco]] (1912), [[Niger]], and [[Tunisia]] (1881).
Egypt, under [[Muhammad Ali of Egypt|Muhammad Ali]] and his successors, conquered [[Nubia]] (1820-22), founded [[Khartoum]] (1823), and conquered [[Darfur]] (1874). Egypt, including the Sudan, became a British protectorate in 1882. Egypt and Britain lost control of the Sudan from 1882 to 1898 as a result of the [[Mahdist War]]. After its capture by British troops in 1898, the Sudan became a Anglo-Egyptian [[condominium (international law)|condominium]].
[[Spain]] captured present-day [[Western Sahara]] after 1874. In 1912, [[Italy]] captured [[Libya]] from the Ottomans.
===Modern times===
Egypt became independent of Britain in 1936, although the [[Anglo-Egyptian Treaty]] allowed Britain to keep troops in Egypt and maintained the British-Egyptian condominium in the Sudan. British military forces were withdrawn in 1954.
Most of the Saharan states achieved independence after [[World War II]]: Libya in 1951, Morocco, Sudan, and Tunisia in 1956, Chad, Mali, Mauritania, and Niger in 1960, and Algeria in 1962. Spain withdrew from Western Sahara in 1975, and it was partitioned between Mauritania and Morocco. Mauritania withdrew in 1979, and Morocco continues to hold the territory.
The modern era has seen a number of [[mining|mines]] and communities develop to exploit the desert's natural resources. These include large deposits of [[petroleum|oil]] and [[natural gas]] in [[Algeria]] and Libya and large deposits of [[phosphate]]s in Morocco and [[Western Sahara]].
A number of [[Trans-African Highway network|Trans-African highways]] have been proposed across the Sahara, including the [[Cairo-Dakar Highway]] along the Atlantic coast, the [[Trans-Sahara Highway]] from [[Algiers]] on the Mediterranean to [[Kano]] in Nigeria, the [[Tripoli-Cape Town Highway]] from [[Tripoli]] in Libya to [[Ndjamena]] in Chad, and the [[Cairo-Cape Town Highway]] which follows the Nile. Each of these highways is partially complete, with significant gaps and unpaved sections.
==Peoples and languages==
The Sahara is home to a number of peoples and languages. [[Arabic]] is the most widely spoken language in the Sahara, from the Atlantic to the Red Sea. [[Berber people]] are found from western Egypt to Morocco, including the [[Tuareg]] pastoralists of the central Sahara. The [[Beja people|Beja]] live in the [[Red Sea Hills]] of southeastern Egypt and eastern Sudan. The Arabic, Berber, and Beja languages are part of the [[Afro-Asiatic]] language family.
Speakers of [[Nilo-Saharan]] language family also inhabit the Sahara, including [[Fur language|Fur]] of [[Darfur]] in western Sudan and the [[Saharan languages]] of Niger, Chad and western Sudan, which includes [[Kanuri language|Kanuri]], [[Tedaga language|Tedaga]], and [[Dazaga language|Dazaga]].
==Countries in the Sahara==
The following countries are either fully or partially covered by the Sahara.
* {{flagicon|Algeria}} [[Algeria]]
* {{flagicon|Chad}} [[Chad]]
* {{flagicon|Egypt}} [[Egypt]]
* {{flagicon|Libya}} [[Libya]]
* {{flagicon|Morocco}} [[Morocco]]
* {{flagicon|Mauritania}} [[Mauritania]]
* {{flagicon|Mali}} [[Mali]]
* {{flagicon|Niger}} [[Niger]]
* {{flagicon|Sudan}} [[Sudan]]
* {{flagicon|Tunisia}} [[Tunisia]]
* {{flagicon|Western Sahara}} [[Western Sahara]]
==See also==
*[[List of deserts by area]]
==References==
*Michael Brett and Elizabeth Frentess. ''The Berbers''. Blackwell Publishers, 1996.
*Charles-Andre Julien. ''History of North Africa: From the Arab Conquest to 1830''. Praeger, 1970.
*Abdallah Laroui. ''The History of the Maghrib: An Interpretive Essay''. Princeton, 1977.
*[[Hugh N. Kennedy|Hugh Kennedy]]. ''Muslim Spain and Portugal: A Political History of al-Andalus''. Longman, 1996.
*Richard W. Bulliet. ''The Camel and the Wheel''. Harvard University Press, 1975. Republished with a new preface Columbia University Press, 1990.
==Notes==
{{reflist}}
==External links==
{{Commonscat|Sahara}}
*[http://www.saudiaramcoworld.com/issue/200701/seas.beneath.the.sands.htm About Sahara subsurface [[hydrology]] and planned usage of the [[aquifers]]]
{{Deserts}}
[[Category:Palearctic]]
[[Category:Deserts and xeric shrublands]]
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