Now the you know the gist of the story you can get an idea of how this movie relates to imperialism. So there is this land that these native humanoids live on and a group of humans are trying to take control over their land for their own benefit. They want the natives land for their resources and decide the best way is to just knock them out, destroy their land and take over everything they have. This relates greatly to the idea of imperialism, considering imperialism means "the policy of extending the rule or authority of an empire or nation over foreign countries or have control over another country." In this case you can consider the native humanoids as the "foreign country," who we are trying to rule and take control of.

Of course no one says that Imperialism has to end with the country that's trying to take control actually getting what they want. In the end native humanoids fight back and take a stand for their land. Causing an epic battle between the "countries." If you want to know who wins, well then your going to have to watch the rest of the movie to find out.