The origin of the current Mexican cuisine was established during the Spanish colonial era, a mixture of the foods of Spain with native indigenous ingredients. Foods indigenous to Mexico include corn, pepper vegetables, calabazas, avocados, sweet potato, turkey, many beans, and other fruits and spices. Similarly, some cooking techniques used today are inherited from pre-Columbian peoples, such as the nixtamalization of corn, the cooking of food in ovens at ground level, grinding in molcajete and metate. With the Spaniards came the pork, beef and chicken meats; peppercorn, sugar, milk and all its derivatives, wheat and rice, citrus fruits and another constellation of ingredients that are part of the daily diet of Mexicans.