Nearly 95 percent of the Thai population are Theravada Buddhists, though many would argue that Siamese Buddhism has integrated with animist folk beliefs as well as Chinese religions. Thai Buddhism was based on the religious movement founded in the 6th century BC by Siddhartha, later known as the Buddha, who urged the world to relinquish the extremes of sensuality and self-mortification and follow the enlightened Middle Way. Theravada Buddhism was made the state religion in Siam only after the establishment of the Sukhothai kingdom in the 13th century CE. By the 19th century, and especially with the coming to power in 1851 of King Mongkut who had been a monk himself for 27 years, the 'sangha' (monkhood), like the kingdom, became steadily more centralized and hierarchical in nature and its links to the state more institutionalized.