Cambodia, officially the Kingdom of Cambodia, is a country in Mainland Southeast Asia. It borders Thailand to the northwest, Laos to the north, Vietnam to the east, and has a coastline along the Gulf of Thailand on the southwest. It spans an area of 181,035 square kilometres (69,898 square miles), and has a population of about 17 million. Its capital and most populous city is Phnom Penh.

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. The Indianised kingdom facilitated the spread of first Hinduism and then Buddhism to Southeast Asia and undertook religious infrastructural projects throughout the region. In the 15th century, it began a decline in power (the Post-Angkor Period) until, in 1863, it became the French Protectorate of Cambodia.

After the Japanese occupation of Cambodia during the Second World War, it gained independence in 1953. The Vietnam War extended into the country in 1965 via the Ho Chi Minh and Sihanouk trails.