Rather diversified forms of this variety (Moriondo, 1999) are cited as present in the Aosta Valley since 1838, when they appear in the writings by Francesco Lorenzo Gatta. This author ascribed these forms to the group of 'Oriou picciou', i.e. Oriou with small-berry to differentiate them from those with large-berry (Oriou gros). These last Oriou likely belong to the variety we know today as Vien de Nus. Even later writers such as Louis Napoleon Bich (1896) and Adrien Berget (1904) classified and consider these forms of Oriou (the today Petit rouge) as distinct. According to Gatta the name Oriou was used for this variety along the valley between Saint-Vincent and Nus, while the name of Picciourouzo (Petit rouge) prevailed near the town of Aosta.

For the etymology of the name Oriou several assumptions have been advanced. The more recent hypothesis closely links the variety to the Aosta valley, because Orioux would be an inhabited hamlet near Saint-Vincent located 600 m above sea level. This place, un-cultivated today, was once equipped with a must press in common use (Vouillamoz and Moriondo, 2011).

Oriou as a variety native of the Aosta valley was first advanced by Berget (1904). This assumed origin matches with the results of recent genetic analyses, which suggest for Petit rouge direct or indirect kinship relationships with some local varieties including Cornallin, Fumin, Vien de Nus and Roussin (Vouillamoz and Moriondo, 2011).

The different forms of Oriou mentioned in the past and partly retrieved in the vineyards today (Moriondo, 1999) have all been attributed to the single grape variety Petit rouge. Among these different forms, Petit rouge or Oriou Lombard is the most common, Oriou picciou the less vigorous, Oriou gris exibitspoorly colored berries, while Oriou voirard and Oriou curant are prone to more or less intense coulure.

Petit rouge is one of the most cultivated grapes in the Aosta valley, from Saint-Vincent to Avise along both banks of the Dora river (Moriondo, 1999).

Petit rouge is a fertile and productive variety. It generally provides wines to be consumed within the second year of production. Wines have an attractive and bright ruby red color, low acidity and a typical scent of red fruits and, at times, wild roses. Many PDO red wines from the Valle d'Aosta, notably those from the areas of Nus, Torrette and Enfer d'Arvier, are made from Petit rouge grapes.