New Spain was a colonial territory established by the Spanish Empire in the Americas during the 16th century. It included parts of present-day Mexico, the southwestern United States, and various Central American countries. The capital was Mexico City, built on the ruins of the Aztec city of Tenochtitlán. The colony was rich in resources, particularly silver, which fueled Spain's economy. New Spain played a significant role in the transatlantic trade, connecting Europe, Africa, and the Americas. It also saw the spread of Catholicism through missions and the establishment of a complex social hierarchy influenced by race and class.