Centuries of rivalry made Cambodians fear Vietnamese domination and Vietnamese resent Chinese pressure.
Vietnam and Cambodia had a long, unequal history. From the 1600s, Vietnamese settlers and armies moved south into the Mekong Delta, once Khmer land. Many Cambodians feared that Vietnam wanted to absorb their country.
Vietnam and China also had a history of conflict. China ruled Vietnam for about a thousand years, until 939, and invaded several times after that. Vietnamese nationalism was built partly on resisting China.
Communist links did not remove these fears. In 1930 Ho Chi Minh founded a single Indochinese Communist Party for Vietnam, Laos and Cambodia. Khmer communists, including Pol Pot, came to see this as a sign that Hanoi wanted to dominate them.
These old animosities did not cause the war on their own. But they shaped how each side read the others' actions after 1975, turning disputes into deep mistrust.
- Chinese rule of Vietnam
- About a thousand years, ending in 939.
- Indochinese Communist Party
- Founded by Ho Chi Minh in 1930 for all three countries.
- Mekong Delta
- Once Khmer land, settled by Vietnamese from the 1600s.
Worked example: Using history as a factor in an essay
How far did historical animosities shape the Third Indochina War?
- Background: Khmer fear of Vietnamese expansion; Vietnamese resistance to China.
- Effect: they made each side assume the worst of the others.
- Limit: animosities existed for centuries without this war, so a trigger was needed.
- Link: Cold War alignments after 1975 turned old fears into open war.
Watch out for this
Communist states could not fight each other because they shared an ideology.
The Third Indochina War was fought between communist states. National interests and historical fears outweighed shared ideology.
Check your understanding
Why did many Khmer communists distrust Hanoi?
- They feared Vietnam wanted to dominate Cambodia, as the old Indochinese party suggested.
- Vietnam had refused to support communism.
- Vietnam was allied with the USA.