In the center of Mexico — in the region where we today find Mexico City — is the Valley of Mexico, a fertile highland plateau located some two thousand meters above sea-level, and surrounded by mountains and several volcanoes which are at least twice as tall. People have lived here for some 12,000 years and it has always been one of the most densely populated regions in the world. Today the urban sprawl which is the Mexico City Metropolitan Area has an estimated 27 million inhabitants. Two thousand years ago it was the city of Teotihuacán which dominated the valley. With its estimated 125,000 people it was the largest city in the Americas at the time, and it was so crowded that some of the inhabitants even had to live in multi-story apartment buildings. Teotihuacán traded with most of today’s Mexico and with much of Central America, and until the city was sacked and burned in 550 CE it was a main adversary of the Mayan empire. Today Teotihuacán is the most visited archaeological site in Mexico, famous for the large pyramids located along the so called “Avenue of the Dead.” The Pyramid of the Sun was both the political and the religious center of the city.
Once Teotihuacán began to decline in the sixth century CE power shifted to Tula, capital of the Toltec empire, a bit further to the northwest. In Tula too we find impressive pyramids, and the architecture of the Toltecs had a profound influence on its neighbors and, much later, on the Aztecs. Ceramics from Tula have been found all over Central America and cultural influences spread at least as wide. This was when the cult of the Feathered Serpent, a god associated with the city of Tula, became a common form of worship. [Read more: Teotihuacán and Tula] Subsequent kingdoms that rose to prominence in the Valley of Mexico, including the Aztecs, would bolster their power by claiming their heritage from the Toltecs.
The power of Tula too lasted about 500 years. Instead of being replaced by another large empire, however, it was replaced by an entire system of states. After the year 1000 CE, a number of city-states, known as altepetl, sprung up in the Valley of Mexico — in the sixteenth-century there were as many as fifty of them. Each city-state was led by a king, tlatoani, who controlled all land and acted as the political, military and religious leader. The tlatoani spoke in the name of the people, he was the source of law and wisdom, and the one who interpreted and carried out the will of the gods. In return he had the right to collect taxes. Each city-state was rigidly hierarchical. Under the king there was a class of noblemen, and under them a class of warriors whose rank varied depending on their achievements on the battlefield. The political system was reflected in the layout of the city. The royal palace was at the center, together with the main temple pyramid and the main market square. Around this center lived the nobility while the commoners lived in the outskirts of the city. The noblemen too were regarded as chosen by the gods and this gave them wide-ranging powers, but the city-state was not a dictatorship. The power of the tlatoani was balanced by the power of a royal council and by judges who acted to protect the rights of ordinary people.
Relations between the city-states ranged from the friendly to the openly hostile. Many city-states joined together in alliances and some attached themselves as tribute-bearers to more powerful neighbors. No state dominated all the others and none of them was sufficient onto itself. Wars were common but they tended to be small-scale affairs and they rarely upset the balance of power. It was only by trading with each other that the city-states could survive, and socially and culturally too they were closely connected. Shoppers would visit a neighboring city looking for bargains, and members of the nobility of different states participated in each other’s ceremonies, festivals and funerals. The families of the tlatoani were often related to each other by marriage. Indeed marriages were an important means of establishing political alliances and maintaining the peace. A lower ranking tlatoani would always try to marry off his daughter to a tlatoani of a more powerful state.
It was into this city-state system that the Mexica arrived in the thirteenth-century CE.[Read more: Aztec codices] The Mexica were Nahuatl-speaking people who had started moving south from their legendary homeland of Aztlán, located somewhere in northern Mexico, already some two hundred years previously.[Read more: Independence for Aztlán] Stopping in various places along the way but never settling for more than a couple of decades in one place, they eventually arrived in the Valley of Mexico. As outsiders without a city-state of their own, the Mexica began by hiring themselves out as soldiers and tried to gain a foothold in the system by making alliances with established rulers. The first such alliance was with the city of Culhuacán whose tlatoani allowed them to settle on his territory. Although the Mexica fought successfully in the armies of their adopted state, relations with their masters turned sour once they decided to sacrifice the daughter of the Culhuacán king in honor of their own god. Thrown out in the 1320s, they were once again looking for a home. Next the Mexica allied themselves with the Tepanec state. The Tepanecs too were Nauhatl-speaking migrants who had come from the north. Again they began by working as soldiers and in return they were given the right to build a city for themselves, Tenochtitlan, first established in 1325 CE. [Read more: Tenochtitlan] The location, on an island in the middle of the swampy lake Texcoco, was hardly prime territory, but as it turned out it provided excellent protection from attackers and the shores of the lake were good agricultural land. The city expanded rapidly and since more and more of the new houses were built on stilts in the water, people increasingly traveled around the city by canoe. In 1372, the Mexica appointed a first tlatoani of their own.
In 1426 the Tepanec king died and shortly afterwards the king of the Mexica was murdered. A new group of people came to power in Tenochtitlan who broke off the alliance with Tepanec and instead allied themselves with the city-states of Texcoco and Tlacopan. Together these three states formed an alliance, a triple alliance, which was to become known as the Aztec empire, 1428–1521 CE. The alliance covered political, military and economic matters, and the three states agreed not to fight each other and to cooperate in wars of conquest against other city-states. All spoils of war were to be divided between them as would all taxes collected from conquered towns. Yet warfare was not always the best way to subdue enemies. Often threats of force were enough or lavish gifts or general offers of friendship or membership in an alliance. As a result, the practices of diplomacy and of warfare blended into each other, and even acts of warfare were often highly ritualistic. Instead of massive peasant armies colliding with each other, warfare was understood as a one-on-one combat between noblemen. Once defeated, the enemy was not killed but instead, much as among the Maya, taken back home and sacrificed in a public ceremony.
In the course of the fifteenth-century, the Aztecs created a large empire covering the entire Valley of Mexico and much of Central America. King Moctezuma I, 1398–1469 CE, who was Mexica, was the person responsible for much of this expansion. During his reign, taxes were levied directly on the subdued city-states and a number of extensive building projects were embarked on, including new pyramids. Trade continued to flourish, and the Aztec empire could be described as a series of related marketplaces where you could buy everything from precious metals and construction materials to weapons, fruits, vegetables and herbs. There were also markets that specialized in certain products such as dog meat. Vendors were organized into guilds and depending on their wares they were allocated to different streets. The Aztecs taxed the markets, but only lightly so. A new legal code, established under Moctezuma, laid down the rules for how society was to be organized: only great noblemen and successful solders were allowed to build two-story houses; commoners could not wear cotton clothing; adulterers were to be stoned and thrown into rivers; thieves would be sold off for the price of their theft. The king himself was never to appear in public except on the rarest of occasions.