This parish lies adjacent to the parish of Arroxó and stands out as the most historically interesting within the municipality. Its terrain is largely flat, with A Peniña-Mer reaching its highest point at 492 metres above sea level, while its lowest point is Outeiro, at 432 metres.
The settlement of Proencia once stood around the parish church. Most historians consider it to be of Roman origin, although some argue that it is Suebic.
Remains of this ancient settlement continue to be found. The most archaeologically significant discoveries date from 1945; these included a tomb, a skeleton, two bells and other bronze and pottery artefacts, which are held in the Provincial Museum of Lugo.
Subsequent studies carried out in 2020 led to the discovery of the first horreum (raised granary) with parallel walls in Galicia. It belonged to an Early Roman Empire villa and consisted of a main building and various associated farming structures, the remains of which are still being excavated nearby.
There are several petroglyphs in this parish, many of which are visible, particularly those located on the O Xestal property and others near the church. The significance of these sites lies not only in their intrinsic value but also in their eastern location, far from the Province of Pontevedra, where the main concentration of rocks engravings of Galicia is found.
As for the parish church, the current building stands upon its original Romanesque structure, of which some remains are still preserved, likely dating from the second half of the 12th-century. Inside the church, there are fascinating wall paintings; these underwent restauration during the second decade of this century.
In addition to the various heraldic houses found in this parish, the manor house commissioned in 740 by Lope López de Lemos y Sober, Lord of Ferreira de Pantón and Sober, stands out. Today, the building lies in ruins, with only the exterior façades and part of the roof remaining. The family coat of arms preserved on its walls is the origin of the coat of arms of Sober Municipality.
In this parish, at the village of Sober o Vello, the municipal offices were formerly situated until their relocation to the village of Berea, now known as Sober.
Proendos was the birthplace of Enrique Fernández Llano, author of the first monograph on this municipality, entitled Descripción del Término Municipal de Sober. The book was published in 1977.