Milpa, or mixed, fields may have been cultivated when Mayapan was inhabited. There is evidence that the area around Mayapan was regularly used for slash-and-burn agriculture. Cenotes and underground limestone canals serve as the only source of freshwater in this area, making them essential to support agriculture. Researchers have suggested that Mayapan was an import/export center, and that they often traded luxury goods, such as cotton, salt, and honey, for products of obsidian and metal, which they would have forged. (Paris 2008) (Melbrath & Peraza 2003:29). Today farmers use mixed fields, called the milpa fields, to cultivate maize, beans, squash, watermelons, mangoes, papayas and other crops. Also, citrus fruit such as oranges and limes are often grown within the domestic house groups of the local residents (Russell 2008:16).