Wat Pa Pao is a Shan (Tai Yai) Buddhist temple that serves as a centre for Chiang Mai's Shan community. It was built in the late 19th century. Once a year, Wat Pa Pao plays host to the luk kaeo, or 'crystal sons' young Shan boys about to be ordained into the Buddhist monkhood. Many of these novices travel to Chiang Mai from surrounding Shan communities at Mae Cham, Mae Rim, Chiang Dao and Fang. This annual Shan ceremony is called Poy Sang Long. The Shan live primarily in the Shan State of Burma, but also inhabit parts of Mandalay Division, Kachin State, and Kayin State, and in adjacent regions of China and Thailand. The Tai-Shan people are believed to have migrated from Yunnan in China. The Shan are descendants of the oldest branch of the Tai-Shan, known as Tai Long (Great Tai) or Thai Yai (Big Thai). The Tai-Shan who migrated to the south and now inhabit modern-day Laos and Thailand are known as Tai Noi (Little Tai). The Shan have inhabited the Shan Plateau and other parts of modern-day Myanmar as far back as the 10th century CE. The Shan kingdom of Mong Mao (Muang Mao) became a Burmese vassal state during the reign of King Anawrahta of Pagan (1044-77).