The period of Angkor is the period from approximately the latter half of the 8th century AD to the first half of the 15th century. If precise dates are required, the beginning may be set in 802 AD, when the founder of the Khmer Empire, Jayavarman II pronounced himself universal monarch (chakravartin) and declared independence from Java, and the end may be set in 1431 AD, when Thai invaders from the kingdom of Ayutthaya sacked Angkor and caused the Khmer elite to migrate to Phnom Penh.