Contact in earnest between the two languages began along with the beginning of the Spanish conquest of Mexico in 1519. Prior to that, Nahuatl existed as the dominant language of much of central, southern, and western Mexico, the language of the dominant Aztec culture and Mexica ethnic group. Though the Spanish tried to eradicate much of Mexica culture after their defeat of the Mexica Aztec in their capital of Tenochtitlan in 1521, Aztec culture and the Nahuatl language were spread among a variety of ethnic groups in Mexico, some of whom, like the Tlaxcala, were instrumental allies of the Spanish in their defeat of the Aztec empire. Since a large part of the surviving indigenous population, whom the Spanish hoped to Christianize and assimilate, were part of the now fragmented Aztec culture and thus speakers of Nahuatl, the Spanish missionaries recognized that they would continue to need the help of their Nahuatl speaking indigenous allies, and allowed them some relative autonomy in exchange for their help in conquering and Christianizing the remainder of the territory, in parts of which indigenous populations remained hostile throughout the 16th century. In this way, friendly Nahuatl speaking communities were valuable in their role as intermediaries between the Spanish and other indigenous groups.