How did the atlantic slave trade benefit the africans?
africans were able to gain protection from the european military during the war. many africans were able to buy land to start their own plantations.
africans eliminated warriors in rival tribes by selling or trading captured prisoners to slave traders.
africans voluntarily migrated to the americas to escape tribal warfare.

the great wall of china worked as a defense for the feudal states of the zhou dynasty to the north. during the warring states period more walls were put up to defend the borders of the different kingdoms. it was semi successful because despite the wall, the mongols eventually conquered china also the great wall provided protection to the economic development and cultural progress, safeguarded the trading routes such as the silk road, and secured transmission of information and transportation. @jayxboof