Sahara

The Sahara (from Arabic ṣaḥrāʾ, “desert”) is largest desert in the world. It is bordered in the west by the Atlantic Ocean, in the north by the Atlas Mountains and Mediterranean Sea, in the east by the Red Sea, and in the south by the Sahel, a semiarid region.

The Sahara has been a major geographical barrier, which has contributed to the development of different races to the north and to the south of the Sahara, the Caucasoids and the Sub-Saharan Africans.