The Aztecs believe that the balance of the natural world and the destiny of people depended on the will of these gods. This is the important idea in Aztec mythology, was that predetermined fate shaped human lives. Some gods were benevolent, while others had terrifying characteristics.
The Aztecs migrated to central Mexico from the north about A.D 1250. Other civilizations such as those of the Olmec and the Toltecs, who had developed a pantheon of gods and mythology, had lived in the region for many centuries.
The Aztecs absorbed deities, stories and beliefs from these earlier people, especially from the ancient Toltec and from the Maya of southern Mexico. As a result, Aztec mythology contained religious and mythological traditions that many groups in Mexico and Central America shared. To the Aztecs, the Toltecs were the originators of all culture. The Aztecs adopted most of the Toltec/Nahua pantheon, but they also made significant changes in their religion.
The main idea in Aztec mythology was that the people were servants of the gods. The power of the gods should be admitted and they had the responsibility of keeping the gods fed, otherwise, disaster could strike at any time. The food of the gods was a precious substance found in human blood. They need to satisfy the gods, especially Huitzilopochtli (the sun god and war god), as the main deity in Aztec mythology. This then, was the origin of human sacrifice.
The Aztecs were built monumental ceremonial centers and there were so many religious rites, in order to maintain the existence of the gods and their goodwill. Aztec religious life ranged from keeping small pottery statues of the gods in homes to attending elaborate public ceremonies involving human sacrifice. Priests conducted ceremonies at the temples. To prepare for the ceremonies, the priests performed a ritual called bloodletting, which involved pulling barbed cords across their tongues or other body parts to draw blood.
Human sacrifice was related to another Aztec myth, that of death and rebirth. The Aztecs believed that the world had died and been reborn several times and that the gods also died and were reborn.
Another idea in Aztec mythology was that of duality, a balance between two equal and opposing forces. Many of the Aztec gods and goddesses were dualistic, mean that they had two sides or roles. For instance, the duality Tlaloc/Huitzilopochtli represents the duality of water and fire.