A semi-nomadic Eurasian tribe, probably of Turkic linguistic affiliation. They are mentioned in the documents from the latter half of the sixth century CE in connection with the westward migration of the Eurasian Avars. When the Avars arrived, according to Theophylactus Simocatta, "the Barsilt (the Barsilians), the Onogurs and the Sabirs were struck with horror ... and honoured the new-comers with brilliant gifts."

They may be identical with the "Bagrasik", included in the list of the steppe peoples north of Derbend in the Syrian compilation of Zachariah Rhetor .

In an Armenian geography of the seventh century, they are described as living on an island. It describes them as distinct from the Bulgars and Khazars and at odds with both nations. In addition, it describes them as possessing large flocks of sheep, supporting the notion that they were at least partly nomadic. M.I. Artamonov theorized that "Barsilia" was located in northern Daghestan, but subsequent scholars have disputed this theory, as the population of the relevant period and region appears to have been, for the most part, settled in permanent fortress-towns.

Some archeologists believe that the Barsils lived near the Volga delta, which would explain the Armenian reference to them as island-dwellers. This is supported by Theophanes' statement that the "populous people of the Khazars came out from the innermost parts of Bersilia in Sarmatia Prima." If indeed they lived on the lower Volga, they were almost certainly conquered by the Khazars, whose capital Atil was in the same region from the mid-700's on.

Eventually at least part of the Barsil nation is believed to have settled in Volga Bulgaria. In the tenth century, ibn Rustah reported that the three nations of Volga Bulgaria were "Bersula", "Esegel", and "Bulgar". Thereafter the Barsils were likely assimilated by the Volga Bulgars.

See also: Aq Bars