The Mesoamericans contributed to the Information Revolution with the Aztecs establishing a great military force, the chinampa of the Aztecs used a small rectangular area of fertile land to grow crops on the shallow lake beds, the use of rubber is documented in the Maya ball game called tlachtli (talithi), they used cocoa beans as a currency, the Maya developed an accurate calendar, also known as the Mayan Calendar, the Quipus are used by the Incan for book-keeping, and the Mita system was invented by the Inca.