<P> The Sahara once had a very different environment . In Libya and Algeria , from at least 7000 BC , there was pastoralism , the hearding of sheep , goats , large settlements , and pottery . Cattle were introduced to the Central Sahara ( Ahaggar ) from 4000 to 3500 BC . Remarkable rock paintings ( dated 3500 to 2500 BC ) , in places which are currently very dry , portray vegetation , and animal presence rather different from modern expectations . </P>
<P> The Sahara once had a very different environment . In Libya and Algeria , from at least 7000 BC , there was pastoralism , the hearding of sheep , goats , large settlements , and pottery . Cattle were introduced to the Central Sahara ( Ahaggar ) from 4000 to 3500 BC . Remarkable rock paintings ( dated 3500 to 2500 BC ) , in places which are currently very dry , portray vegetation , and animal presence rather different from modern expectations . </P>
when did the trans saharan trade routes begin
when did the trans saharan trade routes begin
at least 7000 BC
at least 7000 BC