Then, in April 1519, Spanish conquistadors, led by Cortés, arrived on the coast of Mexico. In August they marched to Tenochtitlan, the capital of the Aztec Empire. At first, Montezuma II, the Aztecs' ruler, invited the Spanish into Tenochtitlan, and things were friendly. Even when the Spanish made Montezuma II a prisoner, the Aztecs stayed friendly.