Eurosia (or Orosia) is the patron saint of Jaca, a city in the province of Huesca of northeastern Spain, in the Pyrenees, the centre of her cult.

A Moorish captain named Aben Lupo planned to wed Eurosia for himself and attacked the Bohemian party.

[2] A shepherd of Yebra de Basa is said to have discovered her relics in the 11th century thanks to an apparition of the Virgin Mary that identified their resting place.

Her head remained at the original simple shrine, while Sancho Ramírez, recognizing the importance of Eurosia's relics, brought her body to Jaca, which he had designated the capital of his kingdom of Aragon.

Her cult spread throughout Béarn and northern Italy thanks to the subsequent campaigns of the Spanish realm in those regions.

Until 1947, when the bishop of Jaca prohibited the practice, those who were afflicted with possession were brought together in a procession and followed an urn carrying her relics.