Cambodian irredentism

The post-Angkor period of Cambodia, also called the Middle period, refers to the historical era from the early 15th century to 1863, the beginning of the French protectorate of Cambodia. As reliable sources are very rare, a defensible and conclusive explanation that relates to concrete events that manifest the decline of the Khmer Empire, recognised unanimously by the scientific community, has so far not been produced. However, most modern historians have approached a consensus in which several distinct and gradual changes of religious, dynastic, administrative and military nature, environmental problems and ecological imbalance coincided with shifts of power in Indochina and must all be taken into account to make an interpretation. In recent years scholars' focus has shifted increasingly towards human–environment interactions and the ecological consequences, including natural disasters, such as flooding and droughts.

Preah Vihear is a province (khaet) of Cambodia. It borders the provinces of Oddar Meanchey and Siem Reap to the west, Kampong Thom to the south and Stung Treng to the east. Its northern boundary forms part of Cambodia's international border with Thailand and Laos. Its capital is Preah Vihear.

The Third Indochina War was a series of interconnected armed conflicts, mainly among the various communist factions over strategic influence in Indochina after Communist victory in South Vietnam, Laos, and Cambodia in 1975. The conflict primarily started due to continued raids and incursions by the Khmer Rouge into Vietnamese territory that they sought to retake. These incursions would result in the Cambodian–Vietnamese War in which the newly unified Vietnam overthrew the Pol Pot regime and the Khmer Rouge, in turn ending the Cambodian genocide. Vietnam had installed a government led by many opponents of Pol Pot, most notably Hun Sen, a former Khmer Rouge commander. This led to Vietnam's occupation of Cambodia for over a decade. The Vietnamese push to completely destroy the Khmer Rouge led to them conducting border raids in Thailand against those who had provided sanctuary.

The Cambodian–Vietnamese War was an armed conflict between Democratic Kampuchea, controlled by Pol Pot's Khmer Rouge, and the Socialist Republic of Vietnam. The war began with repeated attacks by the Kampuchea Revolutionary Army on the southwestern border of Vietnam, particularly the Ba Chúc massacre which resulted in the deaths of over 3,000 Vietnamese civilians. On 23 December 1978, 10 out of 19 of the Khmer Rouge's military divisions opened fire along the border with Vietnam with the goal of invading the Vietnamese provinces of Đồng Tháp, An Giang and Kiên Giang. On 25 December 1978, Vietnam launched a full-scale invasion of Kampuchea, occupying the country in two weeks and removing the government of the Communist Party of Kampuchea from power. In doing so, Vietnam put an ultimate stop to the Cambodian genocide, which had most likely killed between 1.2 million and 2.8 million people — or between 13 and 30 percent of the country’s population. On 7 January 1979, the Vietnamese captured Phnom Penh, which forced Pol Pot and the Khmer Rouge to retreat back into the jungle near the border with Thailand.

Army and warfare made their first appearance in Vietnamese history during the 3rd millennium BC. Throughout thousands of years, wars played a great role in shaping the identity and culture of people inhabited the land which is modern day Vietnam. Vietnam is considered one of the most peace-loving countries in Southeast Asia, and there is even greater belief that Vietnam can be the most peace-loving country in Southeast Asia and one of the most peaceful countries in Asia and the world.

The Dângrêk Mountains, also the Dângrêk Range, is a mountain range forming a natural border between Cambodia and Thailand. Anlong Veng is the final stronghold of the Khmer Rouge of Democratic Kampuchea and the Maoist dictator Pol Pot which is also the final resting place in his jungle headquarters.

Preah Vihear Temple is an ancient Hindu temple built by the Khmer Empire, located on top of a 525-metre (1,722 ft) cliff in the Dângrêk Mountains, in the Preah Vihear province of Cambodia.

The largest of the ethnic groups in Cambodia are the Khmer, who comprise 95.8% of the total population and primarily inhabit the lowland Mekong subregion and the central plains. The Khmer historically have lived near the lower Mekong River in a contiguous arc that runs from the southern Khorat Plateau where modern-day Thailand, Laos and Cambodia meet in the northeast, stretching southwest through the lands surrounding Tonle Sap lake to the Cardamom Mountains, then continues back southeast to the mouth of the Mekong River in southeastern Vietnam.

Khao Phra Wihan National Park is a protected natural area in Sisaket Province, Thailand, that contains numerous ruins of the 11th century Khmer Empire. The park lies 98 km (61 mi) south of the town of Sisaket, at the end of Thai highway 221. Sited on a red stone cliff that is part of the Dangrek mountain range on the southern edge of the Khorat Plateau, it abuts the international border between Thailand's Sisaket Province and Cambodia's Preah Vihear Province. The name of the cliff in the Royal Thai General System of Transcription is Pha Mo I Daeng (ผามออีแดง). The park was established on 20 March 1998, with an area of 81,250 rai ~ 130 square kilometres (50 sq mi).

Cambodia–Vietnam relations take place in the form of bilateral relations between the Kingdom of Cambodia and the Socialist Republic of Vietnam. The countries have shared a land border for the last 1,000 years and share more recent historical links through being part of the French colonial empire. Both countries are members of the Association of Southeast Asian Nations (ASEAN).

The Cambodian–Thai border dispute began in June 2008 as part of a century-long dispute between Cambodia and the Thailand involving the area surrounding the 11th-century Preah Vihear Temple, in the Dângrêk Mountains between Choam Khsant District, Preah Vihear Province of northern Cambodia and the Kantharalak District, Sisaket Province of northeastern Thailand.

Bilateral relations between Cambodia and Thailand date to the 13th century during the Angkor Era. The Thai Ayutthaya Kingdom gradually displaced the declining Khmer Empire from the 14th century, French protectorateship separated Cambodia from modern Thailand at the turn of the 19th–20th centuries, and diplomatic relations between the modern states were established on 19 December 1950.

Khmer nationalism is a form of nationalism found in Cambodia, that asserts that Khmers (Cambodians) are a nation and promotes the cultural unity of the Khmer (Cambodian) race.

The Cambodia–Thailand border is the international border between Cambodia and Thailand. The border is 817 km (508 mi) in length and runs from the tripoint with Laos in the north-east to the Gulf of Thailand in the south.

The Cambodia–Laos border is the international border between Cambodia and Laos. The border is 555 km in length and runs from the tripoint with Thailand in the west to tripoint with Vietnam in the east.

The Cambodia–Vietnam border is the international border between the territory of Cambodia and Vietnam. The border is 1,158 km in length and runs from the tripoint with Laos in the north to Gulf of Thailand in the south.

The Dangrek genocide, also known as the Preah Vihear pushback, is a border incident which took place along the Dangrek Mountain Range on the Thai-Cambodian border which resulted in the death of many mostly Sino-Khmer refugees who were refused asylum by the Kingdom of Thailand in June 1979.