Aztec month Etzalcualiztli, 16th century. Illustration of an Aztec god (probably Tlaloc) representing the month of Etzalcualiztli (Meal of Maize and Beans). Aztec months (non-lunar) lasted 20 days (letters down centre). The rim-eyed rain god is holding a stalk of maize and a water vessel. This month corresponds most closely to the Gregorian month of June, marked by 'Junius', and the crab and moon symbol. 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.