What is the MAIN reason population levels in the Sahara are so low?

The Saharas climate consists of basically two sub climates a dry subtropical climate in the north and a dry tropical climate in the south.

Because it is a Desert

Explanation:

Since it is a Desert, it is very hard to live there, as there is little water, and hotness. It is very dry and there is little food, as crops cannot grow.

yes, since there is a positive and a negetive if the positive and negitive wasn't there wouldn't a flow electricity in it.