The Astures joined the Cantabri in a common defense. In spring 25 BC, there were three Roman legions established near the Astura River (modern Esla River), with troops from Hispania Tarraconensis. According to the contemporary Roman historian Florus in his "Epitome of Roman History", the forces of the Astures Transmontani came down from their snow-covered mountains (which is perfectly possible in the Picos de Europa in spring) and assembled near the Astura River, preparing to attack the three Roman winter camps.