Aztec month Etzalcualiztli, 16th century. Illustration representing the month of Etzalcualiztli (Meal of Maize and Beans). Aztec months (non-lunar) lasted 20 days. The name of each day of the month is shown pictorially. At top is a man with a quetzal plume, standing in water and holding a stalk of maize and a water vessel. This was the sixth Aztec month, corresponding to 9-28 June in the Gregorian calendar. The Aztecs ruled in central Mexico from 1428 until their defeat by Spanish conquistadors in 1521. Artwork from a 19th-century copy of a 16th-century post-conquest history of the Aztecs by Jesuit missionary Juan de Tovar.