The Aztec culture had a fully developed mythological world, that included gods, spirits, demons, other worlds, and several realms of the dead. Their mythology placed a strong emphasis on cycles, and on sacrifice. This view had a large impact on the Aztec afterlife.

Many cultures see the afterlife as a place of judgement, where the way a person conducts themselves in life determines what happens to them after death. The Aztec afterlife did not share this view. Where a person went when they died was determined almost entirely by what caused their death.

The warrior culture of the Aztecs was probably strongly reinforced by the structure of their afterlife, as, much like the Norse, the best afterlife was reserved for warriors, women who died in childbirth, and human sacrifices, which is also why some, though far from all, sacrifices were voluntary. In this view, women who died in childbirth were seen as female warriors who fought to bring new life to the Aztec empire. These heroes spent their afterlife in a celestial paradise, where they would aid the sun god in his journey for part of the day, and spend the rest of the time sipping from flowers and enjoying their well earned paradise.

This celestial paradise was the one place where a deceased conduct during life mattered - to enter it one had to live a hero’s life, as well as die a hero’s death.

The realm of Tlaloc, the rain god, was Tlalocan, where those who died by drowning, lightning or diseases that the Aztecs related to water, such as gout or pustules, went when they died. While not as wonderful as the celestial paradise of the warriors, it was a realm of eternal spring, and abundance.

The last Aztec afterlife was Mictlan, a gloomy, sooty place from which there were no exits. This was the final destination for those who died from old age, accident, or disease. Unlike the other Aztec afterlifes, the dead did no go to Mictlan automatically, but had a long journey through many dangers, including a flooded river, obsidian bladed winds, and fierce beasts.

The Aztec understanding of the cycle of life included an understanding that death was a part of life, and just as the corn had to be harvested to feed people, people had to die to feed the gods and continue the cycle of the universe. The Aztec view of the afterlife, with it’s warriors paradise, encouraged people to be willing to risk their lives, so the cycle of the universe could continue, and they could enjoy a warriors reward in the afterlife.

Sources:

http://www.deathreference.com/A-Bi/Aztec-Religion.html

http://en.wikipedia.org/wiki/Human_sacrifice

http://www.aztec-history.net/aztec_religion