The Sahara Desert is a harsh environment for a number of reasons, though its dryness and soaring temperatures are the main ones. The amount of rainfall in the Sahara each year is so miniscule, it is barely worth mentioning (less than 3 cm), this makes it uninhabitable for the
most part. However there is a small group of nomadic people called the Tuareg that live on its outer edges, raising livestock and trading.
The temperatures in this region are almost unbearable, with the average being roughly 50◦ Celsius. However, there have been temperatures as high as 58◦ Celsius recorded in the area. It is not however, the hottest place on earth. That honor goes to the Lut Desert in Iran which has had temperature recordings of 71◦ Celsius.
While the Sahara is now arid desert, it was not always so. As recently as 6000 BCE, grains were grown in the area, and there have even been cave drawings found that depict greenery growing. Parts of the Sahara have been irrigated in recent years, making them usable once more.
Although we envision the Sahara to be vast areas of sand, the reality is that sand only makes up about 30% of the Sahara. The rest is gravel.