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Following the conquest of North Africa by Muslim Arabs in the 7th century CE, Islam spread throughout West Africa via merchants, traders, scholars, and missionaries, that is largely through peaceful means whereby African rulers either tolerated the religion or converted to it themselves.
Early in the twentieth century, rapid economic and technological change, increasing competition among powerful states, and resistance to European domination worked together to destabilize the world system. Underlying tensions and weaknesses led to a series of crises that altered the world in several important ways.
His pardoning of President Nixon