2.  The Valley of Mexico, a mountain basin about 7,500 feet above sea level, served as the home base of several powerful cultures.  The valley had several large, shallow lakes at it center, accessible resources and fertile soil.

3.  The first major civilization of Central Mexico was Teotihuacan, whose ruins lay just outside Mexico City.  At its peak in the 6 th century, Teotihuacan had a population of between 150,000 and 200,000.  It became the center of a thriving trade network that extended far into Central America.  After centuries of growth, the city suddenly declined.

5.  After the fall of Teotihuacan, no single group dominated Central Mexico for decades until around 900 when the Toltecs came to power.  The Toltecs were an extremely warlike people whose empire was based on conquest.  They worshipped a fierce war god who demanded blood and human sacrifice from his followers.

6.  Around 1000 a Toltec ruler named Topiltzin tried to change the Toltec religion.  He called for the people to end human sacrifice and worship a different god, Quetzalcoatl or Feathered Serpent.  The followers of the war god rebelled and Topiltzin was sent into exile.  After his exile, Toltec power began to decline and by the 1200s their reign had ended.  The Story of Quetzalcoatl

8.  The Aztecs arrived in the Valley of Mexico around 1200 C.E.  The Aztecs, who were known as the Mexica, were a poor, nomadic people from the harsh deserts of North Mexico.  They founded Tenochtitlan on an island in Lake Texcoco in 1325.

10.  Over the years, the Aztecs gradually increased in strength and number.  In 1428 they joined with Texcoco and Tlacopan to form the Triple Alliance.  By the early 1500s, they controlled a vast empire that stretched from Central Mexico to the Atlantic and Pacific coasts and south into Oaxaca.

11.  Military leaders held great power and with government officials and priests, they formed the noble class.  Commoners included merchants, artisans, soldiers and farmers who owned their own land.  Enslaved persons, who were captives, were at the bottom.  The emperor was at the top and had absolute power.

12.  Religion played a major role in Aztec society and the Aztecs had about 1,000 gods.  Aztec religious practices centered on elaborate public ceremonies designed to communicate with the gods and win their favor.  The most important rituals involved a sun god, Huitzilopochtli.  He made the sun rise every day and required human blood for nourishment.

14.  Sacrificial victims included enslaved persons, criminals and people offered as tribute.  Prisoners of war were the preferred victims and as a result priests needed a steady supply of war captives.  The Aztecs often went to war not to conquer new lands but to capture prisoners for sacrifice.

15.  In 1502 a new ruler, Montezuma II, was crowned emperor and under him the empire would began to weaken.  With the population of Tenochtitlan ever greater, Montezuma II called for even more tribute and sacrifices.  A number of provinces rose up against Aztec oppression and this began a period of unrest and rebellion.

16.  Over time Montezuma II tried to lessen the pressure on the provinces.  He reduced the demand for tribute payment by cutting the number of officials.  But resentment continued to grow and many Aztecs began to predict that terrible things were about to happen.  The most worrying event was the arrival of the Spanish.  For many Aztecs, these fair-skinned, bearded strangers from across the sea brought to mind the legend of the return of Quetzalcoatl.