Disease, Armor, Guns, and Horses
Answer:
The Monroe Doctrine
Explanation:
The doctrine threatens European nations by not allow more colonization and monarchs rule in the Western Hemisphere. The Monroe Doctrine was a foreign policy issued in 1823 under the presidency of James Monroe.
President James Monroe states that America has never interfered in foreign matters before. When the rights of the Americas jeopard, then it became necessary to get involved in the issue. The United States will not allow colonization and monarchs rule because it will further lead to the establishment of a colony in America.
The fertile plains near the Nile helped the civilization grow
However, determining the precise beginning and ending to any "period" is often arbitrary, since it has changed over time over the course of history.
