He arrived in what is now Mexico in 1519 with a contingent of about 600 soldiers, 16 horses, and some artillery cannons in search of riches, including gold and treasures. There, Cortés allied with native people subject to Aztec rule who resented and were looking for autonomy from Moctezuma II—the king, and supreme sovereign, known as huey tlatoani, at that time (the ninth ruler of Tenochtitlan) and the city that had become the most dominant in central Mexico leading the confederation that formed the great Triple Alliance—and thus became able to conquer it.