The valley stretches from Gulsvik by Lake Krøderen to the border with Hordaland and Sogn og Fjordane.

Ancient routes went to western Norway (Vestlandet) through Valdres and Hallingdal and down Røldal to Odda.

Reflecting this route, Hallingdal and its neighboring valley of Valdres were originally populated by migrants from Vestlandet and spoke a western dialect.

The actual migration routes are hard to map, and the migrants may have intermixed with local hunters from the mountains around the valley.

In recognition of this, Cardinal Nicholas Breakespear, (later Pope Adrian IV) who was in Scandinavia as papal legate in 1153, included these two valleys in the Diocese of Stavanger.

The dance tunes of the valley have a distinct pattern, following three different lines of tradition, one in the south, at Nes, and two in the area of Ål.

[citation needed] From early on, Hallingdal also developed a tradition for langeleik, partly replaced by the fiddle.

Here, as elsewhere, regional dialects are under strong pressure to change due to outside forces such as mass media and increased mobility in society.