The first humans in the Americas are descendants of northeast Asian nomads who had taken part in a series of migrations across the Bering Strait perhaps as early as 30,000 BCE.

Chips of stone tools found near campfire remains in the Valley of Mexico and radiocarbon-dated to around 21,000 BCE represent the earliest evidence of humans in Mexico.

The Valley of Mexico has drawn people from Mesoamerica attracted by its abundant sources of water, easy communication, and plentiful game and vegetation, throughout its long history of human habitation.

The valley is a corridor through which many migrating groups pass and sometimes settle.

During the pre-Columbian era, the valley is in constant turmoil except when central authority and political hegemony exist.

The last nomadic arrivals in the valley are the Mexica, more commonly known as the Aztec.

Although recent linguistic and archaeological work suggests the Aztec may have come from northwest Mexico, their origins are obscure.

According to legend, the Aztec came from Aztlan, a mythical place to the north of the Valley of Mexico around 1100.

They are said to have made their way to the valley guided by the chirps of their sun and war god Huitzilopichtli (meaning "hummingbird on the left").

The inhabitants of the valley view the new arrivals with suspicion and try to prevent their settlement.

...the Valley of Mexico in or about 1168 or 1179.

The Aztec, after much wandering and a few wars, in the early 1300s, reach the marshy islands in Lago de Texcoco (site of present-day Mexico City), where they see an eagle perching on a cactus tree and holding a snake in its beak (an image reproduced on the modern Mexican flag).

According to Aztec legend, this is a sign indicating where they should build their new capital city.

Tenochtitlan is eventually built on an island in Lago de Texcoco and gradually becomes an important center in the area.

Drinking water comes from Chapultepec hill on the mainland, and causeways connect the island to the shores of the lake.

The Aztec establish a monarchy in 1376, naming Acamapichtli as their first king.

The Mexica, continually dislodged by the small city-states that battle one another in shifting alliances, t finally find refuge on small muddy islands in the slowly shrinking Lake Texcoco in 1325 (or, according to some chronicles, 1345).

They establish a small collection of reed huts on the central island (at modern Mexico City), calling it Tenochtitlán and eventually connecting it to the mainland by causeways.

(The term Aztec is today a collective name applied to all the peoples linked by trade, custom, religion, and language to these Mexica founders.

An alternative date for the Mixtec’s founding of Tenochtitlán in the Valley of Mexico’s Lake Texcoco is 1345.

A second group of Aztec at Lake Texcoco settle the island of Tlatelolco, nearby the capital of Tenochtitlán, in 1358.

Aztec domination reaches into most of central and southern Mexico by the early sixteenth century (with the exception of the Mayan areas in the southeast).

Before the settlement at Tenochtitlan, Aztec society was quite simple in its organization and was composed of peasants, warriors, and priest-rulers.

Afterward, and with a much larger population, there is an increasing division of labor and a more complex social structure.

The emperor is selected according to merit from among the ruling dynasty.

The nobility is composed of the high priests, the military, and political leaders.

The merchant class lives apart in the city and has its own courts, guilds, and gods.

Commoners, the largest segment of society, are farmers, artisans, and lower-level civil servants.

The lowest rung of society is composed of conquered peoples brought to Tenochtitlan as slaves.

The political structure of the Aztec empire is based on a loose coalition of city-states under the fiscal control of Tenochtitlan.

The main objective of Aztec expansion is to exact tribute from conquered peoples.

Tributes are in kind: cocoa, cotton, corn, feathers, precious metals and stones, shells, and jaguar skins are among those sent.

The towns also have the obligation to provide soldiers and slaves and to recognize Aztec supremacy and the supremacy of the Aztec god Huitzilopichtli.

Otherwise, towns are basically free to conduct their internal affairs, and Aztec hegemony is never fully consolidated—a fact that will eventually become a major element in the fall of the empire.

The Spanish are ready to assault the city by the summer of 1521.

The battle rages for three weeks, with the superior firepower of the Spanish eventually proving decisive.

The last of the Azrtec emperors, Cuauhtemoc, is captured and killed.

The legend of Cuauhtemoc will be revived in the nineteenth century, and the last Aztec emperor will be considered a symbol of honor and courage, the first Mexican national hero.

Hernán (sometimes referred to as Fernando or Hernando) Cortés, a Spanish adventurer lured by stories of the riches of the Aztec, assembles a fleet of eleven ships, ammunition, and over seven hundred men and in 1519 sets sail from Cuba to Mexico.

The party lands near present-day Veracruz in eastern Mexico and starts its march inland.

Superior firepower, resentment against the Aztec by conquered tribes in eastern Mexico, and considerable luck all aid the Spanish in their conquest of the Aztec.

The Aztec and their allies have never seen horses or guns, the Spanish have interpreters who can speak Spanish, Maya, and Nahuatl (the Aztec language), and perhaps what is most important, Cortés unwittingly has the advantage of the legend of Quetzalcoatl, in which the Aztec are said to have believed that a white god would arrive in ships from the east in 1519 and destroy the native civilizations.

The Aztec emperor, Moctezuma II (anglicized as Montezuma), unwilling to confront the mysterious arrival whom he considers a god, initially welcomes the Spanish party to the capital in November 1519.

Montezuma soon is arrested, and the Spanish take control of Tenochtitlan.

The Aztec chieftains stage a revolt, however, and the Spanish are forced to retreat to the east.