The history of Taoism stretches throughout Chinese history. Originating in prehistoric China, it has exerted a powerful influence over Chinese culture throughout the ages. Taoism evolved in response to changing times, with its doctrine and associated practices being revised and refined. The acceptance of Taoism by the ruling class has waxed and waned, alternately enjoying periods of favor and rejection. Most recently, Taoism has emerged from a period of suppression and is undergoing a revival in China. Sinologist identifies four components in the emergence of Taoism: