Short answers, pulled from the story.
Jayavarman II declared himself king in 802 AD. This declaration marked the beginning of the Khmer Empire, which grew to become Southeast Asia's largest empire during the 12th century.
The empire began a decline in power by the 15th century, leading to the abandonment of Angkor in 1432 due to ecological failure and infrastructure breakdown.
Cambodia gained independence from France on the 9th of November 1953. This event occurred during the reign of King Norodom Sihanouk after he had been enthroned following the death of Monivong.
Estimates as to how many people were killed by the Khmer Rouge regime range from approximately one to three million, with a cited figure of two million representing about a quarter of the population.
Vietnamese troops invaded Cambodia in November 1978 in response to border raids by the Khmer Rouge. Peace efforts culminated two years later in October 1991 in a Paris Comprehensive Peace Settlement.
Theravada Buddhism is practiced by more than 95 per cent of the population with an estimated 4,392 monastery temples throughout the country.