Trans-Saharan trade requires travel across the Sahara between sub-Saharan Africa and North Africa. While there is from prehistoric times, trade peaked between the 8th and early 17th centuries. Once upon a time, the Sahara was a very different environment. In Libya and Algeria since at least 7,000 B.C., cattle ranching, sheep and goat grazing, large settlements, and pottery. Cattle were introduced into the Central Sahara (Ahaggar ) from 4000 to 3500 BC. Remarkable rock paintings (dated 3500-2500 B.C.) in places that are now very dry depict flora and fauna that do not exist in the modern desert environment.
As a desert, the Sahara is now a hostile space, separating the Mediterranean economy from that of the Niger Basin. Since Fernand Braudel points out that crossing such an area (especially without mechanized transport) only makes sense if exceptional circumstances result in the expected benefits outweighing the costs and dangers.
Trade starting from about 300 was conducted by camel caravans. According to Ibn Battuta the traveler who accompanied one of the caravans, the average size of a caravan was 1,000 camels; some caravans reached 12,000. Caravans would be accompanied by highly paid Berbers who knew the desert and could provide safe passage from the desert to their fellow nomads. The survival of the caravan was risky and depended on careful coordination. Runners would be sent ahead to the oases so that water could be sent to the caravan when it was still a few days away, as caravans could not easily carry enough water with them to make the full journey. In the middle of the 14th century, Ibn Battuta crossed the desert from Sijilmas through the salt mines at Taghaza to the oasis of Oualata. A guide was sent ahead, and water was delivered on a four-day journey from Oualata to meet the caravan.
There was also an exchange of culture and religion along the Trans-Saharan trade route. These colonies eventually adopted the language and religion of the country and were absorbed into the Muslim world.
The Future of Trans-Saharan Trade
The African Union and the African Development Bank support the Trans-Sahara Highway from Algiers to Lagos via Tamanrasset which aims to stimulate trans-Saharan trade. The route is paved, except for a 200-kilometer stretch in northern Niger, but border restrictions still make traffic difficult. Only a few trucks carry the trans-Saharan trade, especially fuel and salt. Three other highways through the Sahara are proposed: see Trans-African highways for details. The highways are difficult to build because of sandstorms.