It's possible there is a misunderstanding:
* Typo: Perhaps you're thinking of a different book title, or a different time period.
* Fictional work: The phrase "slave world" could refer to a fictional work, in which case more information about the specific work is needed to answer your question.
* Historical context: "Slave world" could be a general term referring to the conditions of slavery in the 1930s, which was a time when slavery still existed in some parts of the world, but not in the United States.
Please clarify your question with more details about the book or context you're interested in.