The previous name of the province was Kampong Pous Thom (Port/City of the Great Snakes). According to local legend, at a lakeside dock near the Sen River, a pair of large snakes inhabited a nearby cave. On every Buddhist holiday, the snakes would make appearances to the people nearby who then began to refer to the area as Kampong Pous Thom. Eventually the snakes disappeared and the name was shortened to Kampong Thom. During the Colonial Cambodia period, the French divided Cambodian territory into provinces and named most of them according to the local popular names for the respective areas.