according to the book "bettas" - "in 1927 a shipment of bettas imported from thailand included a semi albino thought at the time to be a different species and named betta cambodia, later it was of course recognized as only a colour variety. the name cambodia is retained today for the semi albino with a white body and pigmented fins and eyes".
further.. on plakatthai.com - "first produced about 1900, are known to the Siamese as pla kat khmer (Cambodian biting fish), probably from having originated among fanciers in French Indo-China". i know plakat were being bred in malaysia, Burma and vietnam, the cambodians were kicking down some mean fish of their own...