Khmer is spoken by approximately 12.6 million people in Cambodia where it is the official language. It is also a second language for most of the minority groups and indigenous hill tribes there. Additionally one million Khmer native to southern Vietnam and 1.4 million in northeast Thailand speak dialects of Khmer.
Khmer dialects, although mutually intelligible, are sometimes quite marked. Notable variations are found in speakers from Phnom Penh (which is the capital city), the rural Battambang area, the areas of Northeast Thailand adjacent to Cambodia such as Surin province, the Cardamom Mountains, and in southern Vietnam. The dialects form a continuum running roughly north to south. Standard Cambodian Khmer is mutually intelligible with the others but a Khmer Krom speaker from Vietnam, for instance, may have great difficulty communicating with a Khmer native to Sisaket Province in Thailand.