Because the Greek city-states were weak and disorganized to unite after the Peloponnesian War.
You didn’t add any options here but I’ll define feudalism for you. Feudalism is a military hierarchy where the ruler offers troops land in exchange for military service. The individual who accepts this offer is called a vassal. The ruler who offered the land is known as the vassal’s lord.
Answer:
WW1, Roaring Twenties, Dust Bowl, WW2, Cold War
Explanation: