Conversation so far:
What is the Mekong Delta?
The Mekong Delta is the region in southwestern Vietnam where the Mekong River approaches and empties into the sea through a network of distributaries.
What did the Khmer Krom do at the Mekong Delta?
In the 17th century a weakened Khmer state left the Mekong Delta poorly administered after repeated warfare with Siam.

Question: When did Vietnam absorb it?
Self-contained rewrite: When did Vietnam absorb provinces?