Bernard Ato IV was the Viscount of Nîmes of the Trencavel

Trencavel

The Trencavel were an important noble family in Languedoc during the 10th through 13th centuries. The name "Trencavel," originally a nickname and later a family name, may derive from the Occitan words for "nutcracker"...

 family from 1074 to his death.

Bernard Ato was the son of Raymond Bernard of Nîmes and Ermengarde of Carcassonne.

In 1125, Bernard Ato retook Carcassonne

Carcassonne

Carcassonne is a fortified French town in the Aude department, of which it is the prefecture, in the former province of Languedoc.It is divided into the fortified Cité de Carcassonne and the more expansive lower city, the ville basse. Carcassone was founded by the Visigoths in the fifth century,...

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He married Cecilia, daughter of the William Bertrand of Provence

William Bertrand of Provence

William Bertrand , known as William V or Bertrand I or II, was the count and margrave of Provence from 1051 to his death...

, and had four daughters as well as three famous sons:

• Bernard Ato V
  Bernard Ato V
  Bernard Ato V was the Viscount of Nîmes of the Trencavel family from 1129 to his death.In 1138, Bernard Ato swore an oath of fidelity to Alfonso Jordan, Count of Toulouse, along with his brothers Roger of Carcassonne and Raymond of Béziers...
  
  
• Roger I
  Roger I Trencavel
  Roger I Trencavel was the eldest son of Bernard Ato IV, Viscount of Albi, Agde, Béziers, Carcassonne, Nîmes, and Razès. On his father's death in 1130 he inherited Albi, Carcassonne, and Razès, while his younger brother Raymond inherited Agde and Béziers and his youngest brother Bernard Ato V...
  
  
• Raymond I Trencavel
  Raymond I Trencavel
  Raymond I Trencavel was the Viscount of Agde and Béziers from 1130 and Viscount of Albi, Carcassonne, and Razès from 1150. He was a member of the Trencavel family, ruling the lands of the elder branch....
  
  

His daughter Ermengard married Gausfred III of Roussillon

Gausfred III of Roussillon

Gausfred III was the count of Roussillon from 1113 until his death. He was the son and successor of Girard I, who was assassinated prematurely, leaving Gausfred a child. Arnold Gausfred, the young count's uncle, acted as regent until 1121....

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Sources

• Cheyette, Fredric L. Ermengard of Narbonne and the World of the Troubadours. Ithaca: Cornell University Press, 2001.