How did Moctezuma II try to reform the empire before the Spaniards arrived?

Koryŏ built a wall at the Yalu River in the eleventh century to help keep out what enemy?

What role did trade play in the Sassanid and Byzantine Empires and in the tensions between them?

Around 2300 B.C.E., what chieftain conquered Sumer and created an empire?

How did Moctezuma II try to reform the empire before the Spaniards arrived?

According to advocates of Legalism, what characteristics should the ideal government have?

What role did the first rulers of Ur, Uruk, and other Sumerian city-states play?

According to Muhammad, who visited him and commanded him to preach God’s revelations?

Which fifth-century Merovingian leader helped unify the Franks?

The need for a chariot-riding aristocracy was diminished by the introduction of what military advancement?