The Maya had city-states that were not unified. They were tied to each other through a system of economic exchange through trading rather than direct rule through a centralized government. Unlike an empire, Maya political structure was a hierarchical government, where there was a single person or group with the most power and authority, with levels of other people who represents a lesser authority. Individual Mayan rulers had a great power over their own kingdoms, but there was never one Mayan king who ruled over the entire Mayan civilization. The Maya were not unified under one ruler.