Isarn was the Count of Pallars from 920 until his death, and effectively a sovereign prince. He was the eldest of four sons of Raymond I

Raymond I of Pallars and Ribagorza

Raymond I was the first independent Count of Pallars and Ribagorza from 872 until his death. Early speculation made him a scion of the Counts of Toulouse, but he is certainly the "Regimundo comite, filio Luponi comiti . . . in pago Paliarensi" of a 920 document....

, Count of Pallars and Ribagorza

County of Ribagorza

The County of Ribagorza or Ribagorça was originally the independent creation of a local Basque dynasty, later absorbed into the Kingdom of Navarre, and then into the Crown of Aragon. Historically it had a strong connexion with the counties of Sobrarbe and Pallars. Its territory was the valleys of...

. With his younger brother Llop he co-ruled Pallars after his father's death in 920. Their brothers Bernard and Miró co-governed Ribagorza. A fifth brother, Otto (or Ato), was Bishop of Pallars, which allowed the counts, especially Isarn, to effectively control the Church

Roman Catholic Church

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with over a billion members. Led by the Pope, it defines its mission as spreading the gospel of Jesus Christ, administering the sacraments and exercising charity...

 in their territories.

Isarn probably co-governed Pallars with his father from around 900. In 904 he was captured along with seven hundred others during a raid by the Moorish

Moors

The description Moors has referred to several historic and modern populations of the Maghreb region who are predominately of Berber and Arab descent. They came to conquer and rule the Iberian Peninsula for nearly 800 years. At that time they were Muslim, although earlier the people had followed...

 chieftain of Lleida

Lleida

Lleida is a city in the west of Catalonia, Spain. It is the capital city of the province of Lleida, as well as the largest city in the province and it had 137,387 inhabitants , including the contiguous municipalities of Raimat and Sucs. The metro area has about 250,000 inhabitants...

, Lope ibn Mohammed. From the Codex of Roda we know that he remained a prisoner at Tudela

Tudela, Navarre

Tudela is a municipality in Spain, the second city of the autonomous community of Navarre. Its population is around 35,000. Tudela is sited in the Ebro valley. Fast trains running on two-track electrified railways serve the city and two freeways join close to it...

 until 918, when he was liberated by Sancho I of Pamplona

Sancho I of Pamplona

Sancho I Garcés was king of Pamplona from 905 to 925. He was a son of García Jiménez, who was king of "another part of the kingdom" of Pamplona and Dadildis de Pallars, his second wife...

. As count, Isarn founded a convent, Sant Pere de Burgal, at Burghals and made his daughter Ermengardis its first abbess in 945. At that date he signed a charter as Domnus Isarnus comes et marchio dum resideret in Paliarensis regno: "Lord Isarn, count and margrave, while residing in the kingdom of Pallars." Isarn also had a son named William who either predeceased him (before 953) or succeeded him but died without descendents.