I am currently reading India: A History by John Keay, and was rather surprised to learn that the name Cambodia has Sanskrit roots.
The name of Cambodia in the Khmer language is “Kampuchea” (Khmer: ព្រះរាជាណាចក្រកម្ពុជា; Preah Reachanachâk Kampuchea), which derives from Sanskrit Kambujadeśa (कम्बोजदेश; “land of Kambuja“). It is not unique to the modern kingdom of Cambodia: the same name (i.e. Kamboj/Kambuja) is also found in Burmese and Thai chronicles referring to regions within those kingdoms. In the Indian chronicles the Kambuja were a barbarian (in the sense of non-Indian) people in the area of modern Afghanistan. “The application to Southeast Asia has no ethnic content and does not imply any migration of peoples from the original Kambuja; the most likely explanation is that, when Indian traders and Brahmins came into contact with local populations some two thousand years ago, they gave them the names of regions which, in their view, were similarly marginal and remote: the peoples of Southeast Asia, like the barbarian Kamboja, had no castes, did not observe proper food prohibitions and had different rules for marriage.” An origin-myth recorded in theBaksei Chamkrong inscription, dated AD 947, derives Kambuja from Svayambhuva Kamboj, a legendary Indian sage who reached the Indochina peninsula and married a naga princess named Mera, thus uniting the Indian and local races. In this story Kambuja derives from Kambu+ja, and means “descendants of Kambu.”