-They were located in the "Central Highlands" known as "Valley of Mexico" and settled on an island of Lake Texcoco.
1. Huey Tlatoani: supreme ruler.
2. Cihuacóatl: Principal advisor.
3. Tlatocan: advice of the 4 officials.
4. Pochtecas: Merchants, diplomats and spies; officials, judges, tax collectors.
5. Macehuales: Peasants, artisans, builders, artists, dancers, warriors.
6. Tamemes: Chargers and slaves.
-Development of medicine.
-Use of mathematics.
-Development of astronomy.
-Operations of the heart.