En (autonym: aiɲ53 or eɲ33ʔ,[4] also known as Nùng Vẻn) is a Kra language spoken in Vietnam.
In the late 1990s, Vietnamese linguist Hoàng Văn Ma had first recognized that it was not a Tai language, ultimately leading to field work distinguishing En as a separate language.
Researchers have determined En to be one of the Buyang languages.
The speakers of En live in northern Vietnam near the border with Jingxi County, Guangxi.
In 1998, En speakers were found 12 km to the east of Hà Quảng city in Nội Thôn village, Hà Quảng District, Cao Bằng Province.