The document provides information about the Aztec civilization. It describes how the Aztecs found the fertile Valley of Mexico as a place to settle. It discusses the Aztec capital of Tenochtitlan, which was built on an island in Lake Texcoco, and how the Aztecs constructed chinampas or small islands to expand the city. The document also notes that the Aztec Empire received tribute including food, gems, and animals from conquered peoples and used this tribute to feed the large population of the capital city.