Title: Middle Ages.
Question: Along with the movement of peoples, invasion and depopulation, what event started in Late Antiquity and continued into the Middle Ages?

Title: Philadelphia.
Question: What is the main driver of the economy now?

Title: United States presidential election, 2004.
Question: How many States renounced their preferred political party?

Title: Modern history.
Question:
What are European revolutions known as in other countries?