In Buddhist mythology, the Yak?a (Yaksha or Yak) are the attendants of Vai?rava?a, the Guardian of the Northern Quarter, a beneficent god who protects the righteous. The term also refers to the Twelve Heavenly Generals who guard Bhai?ajyaguru, the Medicine Buddha. Wat Phra Kaew (Temple of the Emerald Buddha); full official name Wat Phra Si Rattana Satsadaram is regarded as the most sacred Buddhist temple in Thailand. It is located within the precincts of the Grand Palace. The Grand Palace served as the official residence of the Kings of Thailand from the 18th century onwards. Construction of the Palace began in 1782, during the reign of King Rama I, when he moved the capital across the river from Thonburi to Bangkok.