Telemark consists of several distinct historical regions. It takes its name from the largest of them, which is now called Upper Telemark, but which was historically simply called Telemark. Telemark is named for the Thelir (Þilir in Old Norse), the ancient North Germanic tribe that inhabited what is now known as Upper Telemark since the Migration Period and during the Viking Age. The Norse form of the name was "Þelamǫrk". The first element is the genitive plural case of "Þilir" while the last element is "mǫrk" "woodland, borderland, march".