Manifest Destiny: Manifest Destiny was an ideology popular during the 19th century in the United States. It claimed that it was the country's destiny to expand its territory from coast to coast, often at the expense of Native American tribes.
Imperialism: Imperialism is a policy of extending a country's power and influence through colonization or military force. It was prevalent during the 19th and early 20th centuries when European powers sought to establish colonies around the world.
Treaty of Tordesillas: The Treaty of Tordesillas, signed in 1494 between Spain and Portugal, divided newly discovered territories outside Europe between them. It was an example of territorial expansion as both countries aimed to claim new lands during the Age of Exploration.