In the 19th century, during the French Indochina period, Kampot became a regional administrative center with the status of a state border district as a result of the delimitation of the Kingdom of Cambodia. The Circonscription Résidentielle de Kampot contained the arrondissements of Kampot, Kompong-Som, Trang and Kong-Pisey.

In 1889, French colonial census reports a multi-ethnic community: Kampot town consisted of “Cambodian Kampot” on the Prek-Kampot River and “Chinese Kampot” on the right riverbank of the west branch of the Prek-Thom River. Nearby was also a Vietnamese village, called Tien-Thanh and another Vietnamese village on Traeuy Koh Island. A Malay also existed on Traeuy Koh Island. Additional villages of mixed ethnicity are listed.