Aztec month Hueymiccaihuitl, 16th century. Illustration representing the month of Hueymiccaihuitl (Great Feast of the Dead). Aztec months (non-lunar) lasted 20 days (letters down centre). Two boys are climbing a pole topped by ceremonial objects. Other symbols are a bird with a seed, and food items. The month (late July and early August) was dedicated to Xocotl, the god of fire and the stars. 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.