According to Pliny the Elder, before the arrival of the Romans, A Rúa and the rest of the comarca of Valdeorras was occupied by the Celtiberian Cigurri tribe (also known as the Egurri). The medieval and modern name of the comarca is derived from this tribe meaning "valley of the Cigurri" (Val de Geurres) The Cigurri were part of the Cismontani branch of the Asturian people. They spoke the Celtic Gallaecian language. The Romans under Emperor Augustus invaded in 25 BC leading to the Asturian war which lasted until 19 BC, although there were minor rebellions until 16 BC. Near A Rúa and Petín was the location of the Forum Cigurrorum, the political center of the Cigurri, located on the via Nova (via XVIII) between Bracara Augusta and Asturica Augusta.