The history of Boimorto is bound up with the nearby monastery of Sobrado dos Monxes. Some of its parishes appear in very old documents, as is the case of Dormeá, which, under the name Dormiana, is listed in an allocation to the see of Iria at the Council of Lugo in 569.

It later passed to the cathedral chapter of Santiago de Compostela, a gift from Queen Urraca. But it was the powerful monastery of Sobrado, one of the most influential in Galicia, that shaped the life and the history of the area.