The beginning of the 19th century saw Cambodia carved up between the Siamese in the north and west and the Vietnamese in the east. The Siamese, more closely related to the Khmers through Buddhism and generations of mixed marriage, allowed Cambodian customs to continue, while the Vietnamese, although holding a culture of Confucianism, granted their protectorate a deal of autonomy.
New Emperor, New King, Old Rivals (1820-28)
This relative peace was again shattered in the second decade of the century, as first, Emperor Minh Mang took power in Vietnam, followed by Rama III to the west in 1824.
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History: Between The Elephant And The Dragon, Part 1