"how do you think the existence of nearly 3,000 ethnic groups and 800 languages affect life in countries of the sahara"

  The enormous amount of ethnicities and languages in the countries of Sahara contributed to mainly bad and unwanted things to be happening. In lots of the countries there's big devidence between the ethnic groups and it is not unusual that they have clashes that very often have devastating consequences. The countries of the southern half of Sahara usually have clashes on daily basis and there's open hatred and violence between the different ethnic groups, which also leads to the governments having enormous difficulties in the control of some regions. In the northern half of Sahara there has been a systematic genocide going on for quite some time that is kept behind the curtains, like the example with the Barbers and the Jews of North Africa whose numbers have been significantly falling down and they have been massacred systematically by other groups.

a

"the land of the dead"

the answer would be logic.