Cambodia, officially the Kingdom of Cambodia, is a country in Mainland Southeast Asia. It borders Thailand to the northwest, Laos to the north, Vietnam to the east, and has a coastline along the Gulf of Thailand on the southwest. It spans an area of 181,035 square kilometres, and has a population of about 17 million. Its capital and most populous city is Pā¦Cambodia, officially the Kingdom of Cambodia, is a country in Mainland Southeast Asia. It borders Thailand to the northwest, Laos to the north, Vietnam to the east, and has a coastline along the Gulf of Thailand on the southwest. It spans an area of 181,035 square kilometres, and has a population of about 17 million. Its capital and most populous city is Phnom Penh.