competition between several important political centers in central Mexico such as Xochicalco and Cholula ensued. At this time during the Epi-Classic Nahua peoples began moving south into Mesoamerica from the North, and became politically and culturally dominant in central Mexico, as they displaced speakers of Oto-Manguean languages.
During the early post-classic Central Mexico was dominated by the Toltec culture, Oaxaca by the Mixtec and the lowland Maya area had important centers at Chichén Itzá and Mayapán. Towards the end of the post-Classic period the Aztecs of Central Mexico built a tributary empire covering most of central Mexico. The Aztecs were noted for practicing human sacrifice on a large scale. The distinct Mesoamerican cultural tradition ended with the Spanish conquest in the 16th century, and over the next centuries Mexican indigenous cultures were gradually subjected to Spanish colonial rule.
The Spanish conquest of the Aztec Empire began in February 1519 when Hernán Cortés arrived at the port in Veracruz with ca. 500 conquistadores, and later moved on to the Aztec capital. On his search for gold and other riches, Cortés decided to invade and conquer the Aztec empire.
The ruler of the Aztec empire upon the arrival of the Spaniards was Moctezuma II, who was later killed; his successor and brother Cuitláhuac took control of the Aztec empire, but was among the first to fall from the smallpox epidemic a short time later. Unintentionally introduced by Spanish conquerors, smallpox ravaged Mesoamerica in the 1520s, killing more than 3 million Aztecs. Other sources, however, mentioned that the death toll of the Aztecs might have reached up to 15 million (out of a population of less than 30 million). Severely weakened, the Aztec empire was easily defeated by Cortés and his forces on his second return. Smallpox was a devastatingly selective disease—it generally only killed