Little is known of the language situation prior to the first Cambodian school for the deaf being established in the capital of Phnom Penh in 1997.
Although the language of education is American Sign Language, modified to follow Khmer word order, the Deaf community of Phnom Penh has developed their language with the support of the Maryknoll Deaf Development Programme.
[2] CBDSL shares about 40% of basic vocabulary with Modern Thai Sign Language (MTSL).
What intelligibility there is with American Sign Language, apart from iconic elements, is due to vocabulary that is shared among CBDSL, MTSL and ASL.
No connection with other languages of neighboring countries has been noted.