Jayavarman II declared himself "King" and marked the beginning of the Khmer Empire which flourished for over 600 years, allowing successive kings to dominate much of Southeast Asia and accumulate immense power and wealth. The Indianized kingdom built monumental temples including Angkor Wat, now a World Heritage Site, and facilitated the spread of first Hinduism, then Buddhism to much of Southeast Asia. After the fall of Angkor to Ayutthaya in the 15th century, Cambodia was then ruled as a vassal between its neighbors.