The foundation of this monastic community dates back to the 10th century and is considered the origin of this Benditine Monastery. The will of abbot Randulfo, in 994, who escaped from a monastery to the south, during the incursions of Almançor, contains the first references to this Monastery.
The foundation of the Monastery credits Trutesendo Galindes and his wife Anímia, who followed the peninsular monastic habits and adopted the Rule of Saint Benedict, during the abbacy of Sisnando, between 1085 and 1087.
In 1088, the will of D. Egas Ermiges and his wife Gontinha Eriz donates property and other assets to the Church of the Saviour, for the redemption of their souls.
This church does not correspond to the current Romanesque temple, but its architecture left marks in the construction that would be erected in the 13th century, featuring different periods.
Count D. Henrique donates the Monastery as head of a “Couto” [place of privileges] associated to the Ribadouro, one of the most important families in the Entre-Douro-e-Minho, of which descends Egas Moniz who, according to tradition, would have founded this Monastery.
The family comes from foreign roots, and the first representative, Mónio Viegas I, was born in the Gascogne, according to the information on the Livros de Linhagem [Books of Lineage].