Which development encouraged Arab traders to exchange goods for slaves in sub-Saharan Africa in the 11th and 12th centuries?

Answer    well it was money, power and land

Explanation:

 They are arab

answer; /// the correct answer is evidence of the olmec civilization has been found in southern american in a hot steamy forest, archaeologists have found earthen artifacts at several sites that were evidence of the olmec civilization. these   artifacts were mounds,courtyards and pyramids build of stones, also on top of the mounds were many monuments made of stone, some of these stone structures are very large, they weigh as much as 44

the lowest among the social higher rank were the working class. this class remained detached to the political progression   of the country and was hostile to the other two classes