The river has its source in the Marabiu mountains and flows down to the valley that separates the Yernes y Tameza into two distinct sections, each exhibiting a unique set of terrestrial characteristics.

The municipal term is situated at an altitude ranging from 400 to 1,200 meters, with slopes exceeding 21% in more than half of the surface area.

In the northern part of Yernes y Tamanza, mountains such as Güey Morto and La Lloural, which are composed of siliceous rock, are prevalent.

[3] The area was inhabited during the prehistoric and Roman periods, as evidenced by the discovery of lithic remains in numerous caves within the municipality.

Additionally, during the initial decades of the 20th century, gold medals from the Roman Empire were unearthed in the village of Fuxóu.

In 1579, a papal bull from Pope Gregory XIII allowed Philip II of Spain to confiscate the territory and return it to the Spanish Crown.

Juan de Grijalva, the king's representative, appointed the inaugural town councillors and tasked them with formulating the municipality's ordinances.