Which of the Following Statements Is Not Correct About the History

Which of the following statements is not correct about the history of Africa before the twentieth century?

A) It was referred to as "darkest Africa" by many Westerners, who believed that Africa lacked both civilization and a history.
B) The desiccation of the Sahara Desert in the fourth millennium B.C.E. inhibited communication between Europe and southern Africa.
C) Ships from India and China traded with Africa.
D) Africa remained completely isolated from the rest of the world until the Portuguese explorations of the fifteenth century.
E) Trading societies had appeared in West Africa by the seventh century B.C.E.