Ancient routes went to 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 blended with local hunters from the mountains around the valley. In recognition of this, Cardinal Nicholas Breakespear, who was in Scandinavia as papal legate in 1153, included these two valleys in the Diocese of Stavanger.
From early on, Hallingdal prospered from trading with iron, produced from local marshlands, and developed trading routes throughout the Iron Age. In later centuries, the hallingdal farmers traded cattle over the mountains from west to east. Many known locals were involved in this trade. As the soil in the valley could be barren, trading was necessary for life support. In Norway, Hallings reportedly have a knack for trading even today.
Municipalities with Hallingdal include Flå, Nes, Gol, Hemsedal, Ål and Hol cooperate through the Hallingdal Regional Council. The area is within the jurisdiction area of the Hallingdal District Court (Hallingdal tingrett).
The Old Norse form of the name was Haddingjadalr. The first element seems to be the genitive case of a male name Haddingi, the last element is dalr m 'valley, dale'. The first element is also connected to the word hadr, meaning hair.
 Local Culture
The inhabitants are often called hallinger (singular halling). Halling dialect (Hallingdialekt) is a dialect from Hallingdal. It belongs to a dialect group traditionally spoken in Norwegian mountainous areas.
Hallingdal has developed its own brand of the rosemaling, with a distinct symmetric style, different from the style in Telemark and Valdres. The valley also fostered a number of known painters during the 18th and 19th century.
The music of Hallingdal is traditionally dominated by the hardanger fiddle, which was taken into use from c. 1750. 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. The tunes from Ål are recognized by a distinct rolling on the fiddle-bow, and the tunes are fairly old.
From early on, Hallingdal also developed a tradition for langeleik, partly replaced by the fiddle. The folk music tradition is held alive even today in the valley. After the building of the railway line Oslo-Bergen, the accordion came into use, and many fiddle tunes were adapted to the new instrument – usually a diatonic button accordion. Hallingdal is the only area where the old fiddle music were adapted like this in local tradition.
Halling is the name of an old folk dance that is traditionally used in Norway. Each dancer is alone, in contrast to the more common couple’s dances. The climax of the dance is known as thrown Halling, where the goal is to kick down a hat from a stick. The dance is often called Lausdans meaning loose in Hallingdal and Valdres, but known as the Halling in most other valleys.
 See also
- Stagg, Frank Noel (1956). East Norway and its Frontier. George Allen & Unwin, Ltd. ISBN none.
- Hallingtinget (Rekruttering Til Hallingdal )
- Om Hallingdal tingrett (Hallingdal tingrett)
- Haverkamp, Frode. Hans Fredrik Gude: From National Romanticism to Realism in Landscape (in Norwegian). trans. Joan Fuglesang.