One thing that was going on in England during Swift's lifetime (1667-1745) was the Age of Exploration. Europeans in general, and Englishmen in particular, were sailing all over the globe and discovering new lands and cultures.
When Swift writes of the outlandish cultures that Gulliver discovers, he is, partly, engaging in political allegory. On a simpler level, he is satirizing a whole genre of gee-whiz exploration-discovery literature that was widespread in his time.
People were ready to believe almost anything that an explorer might claim about a far-off people, even some things that are almost as outrageous as Swift's Lilliputians and Brobdingians.
It is interesting that in each land that he visits, Gulliver is taken as a prisoner. Perhaps Swift is hinting that Europeans cannot be merely spectators to the cultures that they were quickly discovering, even if they may have preferred to be so. Cultural diffusion is inevitable.
England was going through a lot of political change during the time that Jonathon Swift wrote his novel 'Gulliver's Travels.' The unpopular German prince George I ascended the throne in 1714. He was aided to the throne by the political party of the 'Whigs' who then used their increase in power to pressurize the Tory opposition party. As Swift himself was a Tory he felt bitter that his friends were being mistreated or even exiled. His biting satire is a response to the injustice he feels in his writing. many educated people however just carried on regardless in their pursuit of culture,art,knowledge .... 'enlightenment.' They felt this was the way to create a dream society where everyone would be happy and there would be no wrong-doing. Swift didn't get with this program at all - he believed that man could never rise above his inherent failings to create this perfect utopian society. Some may say he was very forward-looking when we look at the great dreams of early communism and the resulting corruption of power in some countries.