Wilfred the Hairy in the context of "Louis the Stammerer"

The House of Barcelona was a medieval dynasty that ruled the County of Barcelona continuously from 878 and the Crown of Aragon from 1137 (as kings from 1162) until 1410. They descend from the Bellonids, the descendants of Wilfred the Hairy. They inherited most of the Catalan counties by the thirteenth century and established a territorial Principality of Catalonia, uniting it with the Kingdom of Aragon through marriage and conquering numerous other lands and kingdoms until the death of the last legitimate male of the main branch, Martin the Humanist, in 1410. Cadet branches of the house continued to rule Urgell (since 992) and Gandia. Cadet branches of the dynasty had also ruled Ausona intermittently from 878 until 1111, Provence from 1112 to 1245, and Sicily from 1282 to 1409. By the Compromise of Caspe of 1412 the Crown of Aragon passed to a branch of the House of Trastámara, descended from the infanta Eleanor of the house of Barcelona.

The Bellonids (Catalan: Bel·lònides, Spanish: Bellónidas, French: Bellonides), sometimes called the Bellonid Dynasty, were the counts descended from the Goth Belló who ruled in Carcassonne, Urgell, Cerdanya, County of Conflent, Barcelona, and numerous other Hispanic and Gothic march counties in the 9th and 10th centuries. His most famous grandson was Wilfred the Hairy, who founded the House of Barcelona, rulers of the County of Barcelona from 878, and since 1164 the Crown of Aragon, until the end of the reign of Martin the Humane in 1410.

Since the early years of the 10th century all of the eastern counties of the Hispanic March and the counties of Conflent, Carcassonne, Foix, and Razès of the Gothic March were ruled by Belló's descendants. This would have favored the co-ruling of some territories, and a clan-like network of mutual support, although they would have also been exposed to the risk of endogamy.

Bello (c. 755 – 810) was Count of Carcassonne from 790 until his death. He was the founder of the Bellonid Dynasty of Carcassonne and Razès which reached its apex in Wilfred the Hairy, progenitor of the House of Barcelona.

Bello married Ermentrude de Ampurias, several children have been suggested for him:

Wilfred II or Wifred II, also known as Borrell I or Borrel I (Guifré II Borrell I in Catalan), was Count of Barcelona, Girona, and Ausona from 897 to 911, succeeding his father, Wilfred I the Hairy. His mother was Guinedilda.

Upon his father's death, the patrimony was divided between his sons Wilfred ΙΙ, Sunifred ΙΙ, Miró and Sunyer. Sunyer (the youngest) assisted Wilfred II in the governing of his three counties, as he was a minor at their father's death. Upon Wilfred II's death in 911, his counties passed to Sunyer. Wilfred II founded and was buried at Sant Pau del Camp monastery in Barcelona. The executor of his testament was Bishop Idalguer of Vic.