The Khmer Krom people are ethnic Khmers of southern Vietnam currently. It was separated from Cambodia by historical deals. The estimate from Viet government is 1 million, but UN estimates vary from 5 – 6 million. It depends on who is doing the counting though. The history of Viets expansion into Khmer territory has long been recorded in Khmer textbooks. The Viets never fire the war to control Khmer territory. King Jey Jetha II of Cambodia, in fulfilling the wishes of his Viet queen, allowed the Viets to settle in Cambodia town of Prey Nokor which is known as Saigon in 17th century. The Viet government attempts to quash, by forcing or intermarriage, the Khmer Krom language, religion, and culture ( Khmer is Theravada Buddhist, while the Viet practice Mahayana Buddhism) have, but failed. Many Khmer Krom would like to see Cambodian representative as it used to be. The Cambodian, for its part, needs to concentrate on the vast number of illegal Vietnamese (estimate about 6 million illegal Vietnamese) inside the whole country.
Note: There is a great deal of dislike and distrust between the Cambodian and Vietnamese, even among those who have been living in Cambodia for generations. For Khmers, the Vietnamese migrants are always outsiders known as » Yuon » » យួន » ( term that means Viet), while the Viets consider the Khmer for the lazy people that not farming every bit of available land.