Answer:
"Trans-Saharan trade requires travel across the Sahara between sub-Saharan Africa and North Africa. While existing from prehistoric times, the peak of trade extended from the 8th century until the early 17th century. The Sahara once had a very different environment. In Libya and Algeria, from at least 7000 BC, there was pastoralism, the herding of sheep, goats, large settlements, and pottery. Cattle were introduced to the Central Sahara from 4000 to 3500 BC. Remarkable rock paintings, in places which are currently very dry, portray vegetation, and animal presence rather different from modern expectations."
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