The Aztec Empire, which was at its peak between 1345 and 1521CE, was comprised of a series of city states which were known as altepetl. For the sake of reference, a city state is defined as a city that becomes an independent state or country. Modern-day examples of city states include Singapore, Monaco, and Vatican City.
Getting back to the altepetl, each one was led by a tlatoani, or supreme leader, and a cihuacoatl, or administrator. The tlatoani of the capital city of Tenochtitlan(modern-day Mexico City) was the huey tlatoani, or emperor, of the entire Aztec empire.
In each altepetl, the tlatoani was the owner of all land. It was his responsibility to resolve judicial disputes, lead the army, and oversee the markets.
As his second-in-command, the cihuacoatl handled the financial affairs of the altepetl and was the supreme judge in the judicial system.