One of the early scenes in the trailer features two apes walking through the forest, who stumble upon a group of humans. The apes look just as surprised as the humans do, suggesting that maybe they didn't know that there were still some of them left on Earth. The fact that they've lived in peace all this time would suggest that they've simply stayed away from their homo sapien enemies. Even Caesar himself looks stunned when he and the rest of the apes come to see what's going on. This reunion of warring species kicks off the film's larger plots, and ultimately leads to all-out war.