From here...

Years later, I thought about this when I left Nigeria to go to university in the United States. I was 19. My American roommate was shocked by me. She asked where I had learned to speak English so well, and was confused when I said that Nigeria happened to have English as its official language. She asked if she could listed to what she called my "tribal music," and was consequently very dissapointed when I produced my tape of Mariah Carey. (Laughter) She assumed that I did not know how to use a stove. What struck me was this: She had felt sorry for me even before she saw me. Her default position toward me, as an African, was a kind of patronizing, well-meaning, pity. My roommate had a single story of Africa. A single story of catastrophe. In this single story there was no possibility of Africans being similar to her, in any way. No possibility of feelings more complex than pity. No possibility of a connection as human equals. 

...... This single story of Africa ultimately comes, I think, from Western literature. Now, here is a quote from the writing of a London merchant called John Locke, who sailed to west Africa in 1561, and kept a fascinating account of his voyage. After referring to the black Africans as "beasts who have no houses," he writes, "They are also people without heads, having their mouth and eyes in their breasts."Now, I've laughed every time I've read this. And one must admire the imagination of John Locke. But what is important about his writing is that it represents the beginning of a tradition of telling African stories in the West. A tradition of Sub-Saharan Africa as a place of negatives, of difference, of darkness, of people who, in the words of the wonderful poet, Rudyard Kipling, are "half devil, half child."