Aztec Language
Languages similar to the Aztec language have existed in Central Mexico for perhaps 1400 years. As early as 600AD, languages known as Nahuan were spoken by peoples in the area. It is believed that these language speakers came from the north in waves, settling in central Mexico.
Speakers of languages such as Nahuatl (the Aztec language) began to gain power, and by 1000AD (CE) it is likely that Nahuatl speakers were the dominant power.
One of the last Nahuatl speaking groups to come to the area was the Mexica, who would become a powerful force in the founding of the Aztec empire.
As the empire grew, so did the influence of Nahuatl (also called Classical Nahuatl, Mexicano or Aztec). Naturally, those who wanted to get along with the powers-that-were needed to speak it. It was a language of trade, and a language of prestige. It was used in literature extensively.