In the old time, a Cambodian prince was married to a Vietnamese princess. In return, the Vietnamese government seek to establish a pupet government in the province known as Prey Nokor(today Ho Chi Minh). From there, they start the invased internally by killing all the Khmer Krom leader.
After the French gain control of the Indo-China, the Vietnamese were then claimed that that Lower Part (Kampuchea Krom or today South Vietnam) was belong to them. The French would then force the Khmer king to give away the land or died.
More stuff happen in between but I don't know the rest because of the Vietnamese law forbid the Khmer Krom people to learn their history, and language.
The fact that many Khmer Krom people was murdered by the Vietnamese leaders make the Khmer Krom people so angry at the Vietnamese people. As a result, many Khmer Krom people want to get revenge against the Vietnamese people.
Many people expect the Khmer Krom to give up and become Vietnamese themselve but Khmer Krom people will never give up. They will fight, by word or by force to let the world know their inhumane treatment by the Vietnamese government.
visit here if you want to learn more.
http://www.khmerkrom.orgKhmer Krom 4 Life,
Thay_