Thai sculpture is concentrated on Buddha images that rank among the world's greatest expressions of Buddhist art. As a result, it is widely believed that the Buddha images in Thailand, from the Chiang Saen Period (11-13th c.) to the present Rattanakosin or Bangkok Period, are so numerous that they far outnumber the population of the country. Made in wood, metals, ivory, precious stones and stucco, they have been created to represent Rattanatrai of Buddhism, i.e., Buddha, Dharma (the Buddha's doctrine) and Sanga (Buddhist clergy).Among the most beautiful Buddha images in Thailand are Phra Buddha Chinnarat in Wat Mahathat (Phitsanulok province) and Phra Buddha Chinnasi in Wat Bowon Niwet (Bangkok).