Chinese cuisine is rich and diverse, varying in style and taste from region to region. Its history dates back thousands of years, evolving according to changes in both the environment (such as climate) and local preferences over time. Chinese cuisine also varies depending on class and ethnic background, and it is often influenced by the cuisines of other cultures. All these factors contribute to an unparalleled range of cooking techniques, ingredients, dishes and eating styles that make up what is understood to be Chinese food today.