Appropriately enough, the setting of the story is a farm, somewhere deep in rural England. Although the setting is not the most important aspect of Animal Farm, it still has significance, nonetheless. The story is an allegory of life in the Soviet Union, and the Soviet system was established in a country where the vast majority of people—some 90% of the population—were peasants who made their living off the land. In carrying out their revolution, the Bolsheviks turned Marxist orthodoxy upside-down, establishing communism in a country with an agrarian-based economy which was anything but industrially advanced.
The Animalist revolution is also established in less than propitious circumstances. The farm is the very last place you'd expect downtrodden animals to rise up and throw off the yoke of the hated human oppressor. Yet they do, and in carrying out their revolution, the animals are, like the Bolsheviks in Russia, overturning established orthodoxy. Just as no one would ever have reasonably anticipated a communist revolution taking place in a country of peasants, so too would no one ever dream of farm animals turning against their human overlords and driving them from their midst.