Answer:
O harsh, dry climate
Step-by-step explanation:
People have lived in the Sahara long before recorded history, at certain times in regions that are now too arid for human inhabitance. Archaeological findings indicate that there were once ancient Saharan lakes, upon the shores of which humans lived, hunted, and fished. Even after these lakes ceased to exist, humans survived for centuries in the desert using alternative methods: nomadic pastoralists herded goats, sheep, or camels to whatever pasturage could be found; sedentary agriculturalists, confined to oases, harnessed their limited water resources to grow crops such as date palms and barley; and specialists (for example, blacksmiths) traded wares with their agriculturalist and pastoralist neighbours. Certain groups have long relied on travelling and trading along caravan routes to obtain their livelihood, journeying by camel to oases and population centres all over the Sahara. Modern economic development has disrupted many of these traditional means of subsistence, however, with many desert dwellers seeking more lucrative opportunities in developed regions and oases.