1. Conquest by Alexander - Unifed the know world under one language.
2. Conquest of Egypt by Rome, Brought world under it rule, making it possible to travel from Brittian to tazikastan while only using 2 languages.
3. Discovery of the New World, change the social order.
4. The French Revolution, brought us communism, Nazi, and a whole host of other problems, Ended unquestioned authority by kings and replaced it by unquestioned authority by the state.
5. Americain Revloution - brought us theocratic democracy and freedom we enjoy today.