The kind of Buddhism practiced in Cambodia is called Theravada Buddhism. Buddhism has existed in Cambodia since at least the 5th century CE, with some sources placing its origin as early as the 3rd century BCE.^{[citation needed]}Theravada Buddhism has been the Cambodian state religion since the 13th century CE (excepting the Khmer Rouge period), and is currently estimated to be the faith of 95% of the population.

The history of Buddhism in Cambodia spans nearly two thousand years, across a number of successive kingdoms and empires. Buddhism entered Cambodia through two different streams. The earliest forms of Buddhism, along with Hindu influences, entered the Funan kingdom with Hindu merchants. In later history, a second stream of Buddhism entered Khmer culture during the Angkor empire when Cambodia absorbed the various Buddhist traditions of the Mon kingdoms of Dvaravati and Haripunchai.

For the first thousand years of Khmer history, Cambodia was ruled by a series of Hindu kings with an occasional Buddhist king, such as Jayavarman of Funan, and Suryavarman I. A variety of Buddhist traditions co-existed peacefully throughout Cambodian lands, under the tolerant auspices of Hindu kings and the neighboring Mon-Theravada kingdoms.

Cambodia (ⁱ/kæmˈboʊdiə/;Khmer: ព្រះរាជាណាចក្រកម្ពុជា, Kampuchea, IPA: [kɑmˈpuˈciə]), officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia. With a total landmass of 181,035 square kilometres (69,898 sq mi), it is bordered by Thailand to the northwest, Laos to the northeast, Vietnam to the east, and the Gulf of Thailand to the southwest.

With a population of over 14.8 million, Cambodia is the 68th most populous country in the world. The official religion is Theravada Buddhism, which is practiced by around 95% of the Cambodian population. The country minority groups include Vietnamese, Chinese, Chams and 30 various hill tribes. The capital and largest city is Phnom Penh; the political, economic, and cultural center of Cambodia. The kingdom is a constitutional monarchy with Norodom Sihamoni, a monarch chosen by the Royal Throne Council, as head of state. The head of government is Hun Sen, who is currently the longest serving leader in South East Asia and has ruled Cambodia for over 25 years.