Prehistoric civilizations from the Occasus desert

Some areas on our planet are beautiful. They sunbathe in September, they are visited by people who enjoy the beautiful nature, fauna and flora they do not know at home.
Then there are also inhospitable ends like the Gobi desert with the blooming sand, the inaccessible taiga of the Tunguzka Podkamenné (an ET crash in 1908), the hot Sahara Desert (a stone monument in the form of the Sphinx), so we could go on.
But - was it always so? Have not these places been full of people, animals, plants? Why else would we find in these god-forgotten counties very interesting traces of settlements and civilizations that can not get into school textbooks and wider awareness ...?