Explain the immediate changes experienced by the Aztecs after the arrival of the Spanish in 1519. Refer to any sources in your response.

The Spanish conquest of the Aztec Empire, also known as the Conquest of Mexico (1519-21),[6] was one of the primary events in the Spanish colonization of the Americas. There are multiple 16th-century narratives of the events by Spanish conquerors, their indigenous allies, and the defeated Aztecs. It was not solely a contest between a small contingent of Spaniards defeating the Aztec Empire but rather the creation of a coalition of Spanish invaders with tributaries to the Aztecs, and most especially the Aztecs' indigenous enemies and rivals. They combined forces to defeat the Mexica of Tenochtitlan over a two-year period. For the Spanish, the expedition to Mexico was part of a project of Spanish colonization of the New World after twenty-five years of permanent Spanish settlement and further exploration in the Caribbean.