The belief that the United states had a duty to spread democracy across the continent.
Explanation:
Become the most populous empire in the world.
The Song Dynasty was first civilization in the world to use banknotes, aka paper money. They also were the first to use gunpowder, and the first to make a permanent navy. They were also the first to discern the North using a true compass. They had many, many firsts, which helped develop the world into how it is today.
Sorry, that this is only one half of your answer. But, I hope this still helps.
