Trans-Saharan trade requires travel across the Sahara

Sahara

The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

 to reach sub-Saharan Africa

Sub-Saharan Africa

Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

. While existing from prehistoric times, the peak of trade extended from the 8th century until the late 16th century.
The Sahara once had a very different environment. In Libya

Libya

Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....

 and Algeria

Algeria

Algeria , officially the People's Democratic Republic of Algeria , also formally referred to as the Democratic and Popular Republic of Algeria, is a country in the Maghreb region of Northwest Africa with Algiers as its capital.In terms of land area, it is the largest country in Africa and the Arab...

, from at least 7000 BC, there was pastoralism

Pastoralism

Pastoralism or pastoral farming is the branch of agriculture concerned with the raising of livestock. It is animal husbandry: the care, tending and use of animals such as camels, goats, cattle, yaks, llamas, and sheep. It may have a mobile aspect, moving the herds in search of fresh pasture and...

, herding of sheep and goats, large settlements and pottery. Cattle were introduced to the Central Sahara (Ahaggar) from 4000 to 3500 BCE.