Alternate history is a subgenre of consisting of stories that are set in worlds in which one or more historical events unfolds differently from how it did in this reality. These types of stories explore the "what if" scenarios from some of history's most pivotal turning points and presents a completely different version. The result of these changes are based facts and opinions.
A good example of this subgenre would be Robert Silverberg' "The Gate Of Worlds" novel. The novel is set in a fictional period where the black death kills 3 quarters of the population in Europe, halting the industrial revolution. As the result of this, the Ottoman take over parts of Europe such as France, Italy and England. The Aztecs become the powers of Central and South American while Japan holds the power in the East. This is a very interesting take of a world that is not dominated by European powers.