The Sahara Desert was once a lush, green landscape with lakes, rivers, and grasslands.
Why it is true
Around 10,000 years ago, during the African Humid Period, monsoon rains transformed the region, supporting hippos, crocodiles, and human settlements.
Source: Climate Research
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.