These ruins testify to the presence of the Romans in the Sangro Velly certainly since 298 BC, after the defeat of the Samnite tribes. Most likely, the high Sangro area was placed under the jurisdiction of the Roman Prefecture of Atina (FR). During the late Republican period, the system of settlements was based on a land division in large intensive cultivated plots, ruled by big farms or “villas”, whose ruins have been found also in the municipality of Villetta Barrea. This organisation was a mixed economy based on agriculture and sheep farming, where transhumant sheep farming was the main source of wealth. The shepherds ran over the calles-roads (the so called tratturi during the Roman age), drawing itineraries that have been followed by the transhumance for centuries, until nowadays. During late Antiquity and Early Middle Ages, uphill and mountain settlements continued to be occupied and fortified by the Romans: "castles", that have been overlooking Abruzzo landscape for a long time. After the dissolution of the Roman Empire and with the onset of the Barbarian invasions, many communities settled in the monasteries which turned into fortified shelters. In Villetta Barrea cemetery the ruins of the ancient monastery of St. Angelo in Barreggio are preserved, founded in the 6th century. d.C. and severely damaged in 937 by the Magyars raids. In 1017 the Princes of Capua, Pandulf II and Pandulf III gave his brother Atenulf, Abbot of Montecassino the monastery with all its properties and lands- he restored the basilica on the same place, but moved the convent further down to the valley, on the spur of rock of Foci di Barrea, the "Studio" with its five windows that once overlooked the valley, today are fully walled. In addition to it, the monks built the fortress-monastery of Barrea, the fortified settlement of Rocca Intramonti, today in the municipality of Civitella Alfedena, thus completing the defensive system of the so called Vallis Regis (one of the hypotheses about the etymology of the name is that of "Rea Valley", devoted to the goddess Cybele, Rhea Hellenic goddess of abundance). After the destruction of this fortress by Giacomo Cantelmo, the count of Alvito, the inhabitants of the village inhabited the hills in the surroundings around and new families, under the protection of the monastery of s. Angelo in Barreggio founded Villetta Barrea, quoted for the first time in 1426 as"Villa Vallis Regiae”. From then until the early 19th century, Villetta Barrea was subjected to the struggles amongthe Caldora marqueses of Vasto, the Cantelmo di Alvito counts an the d’Affito family from amalfi, who wanted ti gain the control over the village territory. During this period however, Villetta Barrea saw an increasing in its population and in wealth, thanks to the developing of sheep farming and transumance.