Elfdalian

What has been considered a dialect in central Sweden, the form “Elfdalian” is now recognized as a distinct Nordic language. 

Elfdalian is traditionally spoken in a small part of the region of Dalarna, known as Älvdalen in Swedish and Övdaln in Elfdalian. But using linguistic and archeological data, including runes, Elfdalian experts have tracked the language back to the last phase of ancient Nordic – spoken across Scandinavia between the sixth and eighth centuries...

While runes had became obsolete in most of Sweden as early as the 14th century, there is evidence of runes being used in Älvdalen as late as 1909, making it the last place in the world where they were used.