The Russian Revolution
The most obvious perspective to make when working with Animal Farm is a historical perspective to the Russian Revolution, as the novel is a direct allegory of this revolution and the decades that followed it.
You may draw parallels between events depicted in the novel and the historical realities in the Soviet Union. It may be obvious to look for similarities, but it might also be interesting to consider whether Orwell presents an unfair or incorrect version of some events or people in his allegorical story.
Other historical revolutions
It is also possible to compare the story of Animal Farm to other historical revolutions, as it also tries to display some general tendencies that might be observed. For example, you may consider other examples of revolutions that have left the relevant nation or area in a worse political position than before, or which were based on beautiful ideals in theory, but led to extreme violence and rights violations in practice.
The French Revolution is in some ways an example of both these issues. Even though France eventually became a proper democracy, it first went through an extremely violent period of executions of the former royalty and aristocracy, followed by a period of ...