Rivers are also interesting because sometimes a name applies only to part of the river, even within a single language. For example, in Vietnamese, the overall Mekong River is called sông Mê Kông, but its distributaries are known by a variety of unrelated names, and collectively the river system within Vietnam is known as sông Cửu Long. In other words, the Mê Kông arises in China but the Cửu Long arises at the Cambodia–Vietnam border. In practice, Cửu Long is never translated into English, which applies the same name to the entire river.