How did geographic conditions limit contact between africans and people from outside of the middle east?

Sahara desert was a large isolating buffer that prevents eastern and sub-saharan African peoples from consistent contact with other peoples. The middle east was the only civilzation with land connection to the rest of Africa an stood in between Africans and the rest of the known world.

on april 6, 1917, the u.s. joined its allies--britain, france, and russia--to fight in world war i. under the command of major general john j. pershing, more than 2 million u.s. soldiers fought on battlefields in france.