Cambodia's control of the area grew increasingly tenuous while increasing waves of Vietnamese settlers to the Delta isolated the Khmer of the Mekong Delta from the Cambodian kingdom. By 1757 the Vietnamese had absorbed the provinces of Psar Dèk (renamed Sa Déc in Vietnamese) on the Mekong itself, and Moat Chrouk (Vietnamized to Châu Doc) on the Bassac River.

Khmer nationalist Son Ngoc Thanh