The region now known as Cambodia has been inhabited since prehistoric times. In 802 AD, Jayavarman II declared himself king, uniting the warring Khmer princes of Chenla under the name "Kambuja". This marked the beginning of the Khmer Empire, which flourished for over 600 years. The Indianised kingdom facilitated the spread of first Hinduism and then Buddhism to much of Southeast Asia and undertook many religious infrastructural projects throughout the region. Angkor Wat is the most famous of these structures and is designated as a World Heritage Site. In the fifteenth century, after the rebellion of Ayutthaya, which was formerly ruled by the Khmer Empire, Cambodia experienced a decline of power, while its neighbors Vietnam and Thailand grew stronger. In 1863, Cambodia became a protectorate of France, and later was incorporated into French Indochina. The country was under Japanese occupation during the Second World War before French control was restored.