Italian cuisine has developed through centuries of social and political changes, with roots as far back as the 4th century BCE. Italian cuisine in itself takes heavy influences, including Etruscan, ancient Greek, ancient Roman, Byzantine and Jewish. Significant changes occurred with the discovery of the New World and the introduction of potatoes, tomatoes, bell peppers and maize now central to the cuisine but not introduced in quantity until the 18th century. Italian cuisine is noted for its regional diversity, and is known to be one of the most popular cuisines in the world. Italian cuisine is characterized by its simplicity, with many dishes having only four to eight ingredients. Italian cooks rely chiefly on the quality of the ingredients rather than on elaborate preparation.