How does Sahara desert came into existance?

Question

I want to know whether it being on Earth since the formation of Universe or some environment phenomena brought it into existence.

Answer 1

the prevailing winds & geography are such that the air, by the time it reaches the Sahara, has usually already dumped its moisture.  Result: arid region.

In previous eras Africa and Europe were located in different places and hence Sahara was not always a desert.

Further, even 2000 years ago Sahara was less of a desert than it now is, as has been revealed by archeologists

who found cave paintings of animals & stuff who cannot live in that area under present dry conditions; also deep

radar scans showing former rivers, lakes, etc under the sand, with human settlements by the shores.

That is probably due to humans messing up the place.

They raised goats.  The goats ate the grass.   The grass

stopped holding down the soil which held onto the rain,

and kept things cooler;

and so the sands blew in, it got hot,

and the water sunk.

Then nothing could grow.

The Romans had engineers very carefully designing all kinds of water conservation devices, practices, and landscaping.

They were able to feed their empire by growing stuff in

Libya.

But it sure ain't the breadbasket of the world at present, because after the Romans fell, that stuff was forgotten.

Even over the last 40 years Lake Chad, once one of the larger lakes in the world, has shrunk drastically.  That

represents an expansion of dry regions.

Global warming will alter wind & rain patterns in

ways that probably will cause the Sahara to get even worse and it may even extend into southern Europe.