precise date when the technology was developed, but the earliest evidence of nixtamalization is found in Guatemala's southern coast, with equipment dating from 1200–1500 BC. How nixtamalization was discovered is not known, but one possibility may have been through the use of hot stones (see Pot boiler) to boil corn in early cultures which did not have cooking vessels robust enough to put directly on fire or coals. In limestone regions like those in Guatemala and southern Mexico, heated chunks of limestone would naturally be used, and experiments show that hot limestone makes the cooking water sufficiently alkaline to cause nixtamalization. Archaeological evidence supporting this possibility has been found in southern Utah, United States. The Aztec and Mayan civilizations developed nixtamalization using slaked lime (calcium hydroxide) and lye (potassium hydroxide) to create alkaline solutions. The Chibcha people to the north of the ancient Inca also used calcium hydroxide (also known as "cal"), while the tribes of North America used soda ash. The nixtamalization process was very important in the early Mesoamerican diet, as most of the niacin content in unprocessed maize is bound to hemicellulose, drastically reducing its bioavailability. A population that depends on untreated maize as a staple food risks malnourishment and is more likely to develop deficiency diseases such as pellagra, niacin deficiency, or kwashiorkor, the absence of certain amino acids that maize is deficient in. Maize cooked with lime or other alkali provided bioavailable niacin to Mesoamericans. Beans provided the otherwise missing amino acids required to balance maize for complete protein. The spread of maize cultivation in the Americas was accompanied by the adoption of the nixtamalization process. Traditional and contemporary regional cuisines (including Maya cuisine, Aztec cuisine, and Mexican cuisine) included, and still include, foods based on nixtamalized maize. The process has not substantially declined in usage in the Mesoamerican region, though there has been a decline in North America. Many North American Native American tribes, such as the Huron, no longer use the process. In some Mesoamerican and North American regions, dishes are still made from nixtamalized maize prepared by traditional techniques. The Hopi produce sodium carbonate from ashes of various native plants and trees. Some contemporary Maya use calcium salts in the form of ashes of burnt mussel shells or heated limestone. In the United States, European settlers did not always adopt the nixtamalization process, except in the case of hominy grits, though maize