Though it possesses an engaging history that spans over 5000 years, Chinese culinary history only began to be documented during the 5th Century B.C. and evolved across several dynastic periods including the Han, Tang, Song, Yuan, Ming and Qing dynasties. Imperial oversight played an important role in the development of culinary trends. A cook's buffet chinese work was set to strict culinary rules determined by the emperor and senior officials. China's varied regional, climatic and cultural influences saw the development of vegetarian and non-vegetarian dishes with exclusions that followed the availability or religious significance of certain ingredients. Over the last 2000 years, Chinese cooking saw the development of strong culinary differences across the banks of the Yangtze River. European travellers brought with them dairy products, a class of products rarely found in historical culinary records. The blurring of cultural and geographic lines led to the development of regional cuisines and the 'Four Schools' and 'Eight Schools' of this cuisine as well as several dietary trends. Today, we know these as 'cleansing' or 'balanced' diets. Ancient Chinese cookbooks list nearly 200 distinct vegetables and over 100 types of meat that featured on imperial and common menus throughout the country. Through all these cultural, religious and imperial upheavals, the core philosophy of this cuisine has been moderation, balance and harmony.