The first signs of human settlements in Tertenia date back to the Neolithic (IV-III millennium BC). In the surrounding territories utensils, crockery and fragments of obsidian have been found, along with the multiple tombs of the giants, the domus de Janas and the various nuraghes, including the Aleri nuraghe, the Nastasi nuraghe and the Longu Nuraghe. According to local tradition, originally the town was located on the sea and only following the incursions of the vandals and Saracens it was abandoned by its inhabitants, who found a safer refuge inside, creating a new village halfway up the Monte Giuilèa, where they lived for a long time until, due to the friable and landslide terrain, they decided to go down to the valley where they fixed their new homes, giving life to today's center.
In the Middle Ages Tertenia was part of the Giudicato of Cagliari, in the curatoria of Sarrabus, of which it was the capital. At the fall of the Giudicato it passed for a short time to the Giudicato of Gallura, then under the Pisan domination and from 1324 to the Aragonese, under whose dominion it was annexed to the county of Quirra. Around the sixteenth century, the tower of San Giovanni di Sarrala was built to watch over the coast. In 1839 the town was finally redeemed from the Osorio family, the last feudal lords, with the abolition of the feudal system, becoming an autonomous municipality.
Tertenia is the southernmost town in Ogliastra. It is located at the foot of Mount Giuilèa, about 120 meters above sea level and has about 3900 inhabitants. The inhabited center develops along the Rio Quirra valley, at the foot of the rocky complex of calcareous heels. The geology of the territory is quite varied and complex: the sa Serr'e Mari chain, which separates the town from the coastal slope, Mount Cartuccedu and Monte Ferru are composed of rosy granite-porphyritic rocks. In the marina there are plains and hills, long beaches (Fogi Manna, Fogi 'and Murdegu) and rocky coasts. To the west is the Taccu plateau, with the highest peak in Mont'Arbu and the lowest peak in Tacchigeddu, of the calcareous-dolomitic formations typical of the area that dominate predominantly schistose rocks, on which the historical nucleus of the town is also built .
The main watercourse is the Quirra river, composed of the tributaries Corongiu, Su Santu, and Baccu Longu: it cuts the territory in a north-south direction, while there are numerous seasonal streams. The spontaneous vegetation is shrubby, with two vast forests, Su Crabiolu and Fustiragili. From the landscape and environmental point of view, the Tertenian territory offers a fascinating combination of the sea and the mountains.
Tertenia can boast among its illustrious citizens one of the Sardinian artists who best stood out both nationally and internationally in the last century, Albino Manca. The most viewed artwork in the world is the Tertenian artist, the Diving Eagle: an impressive bronze sculpture, representing a swooping eagle positioned in Battery Park, in the waterfront of the island of Manhattan in New York. The work was inaugurated by the President J.F. Kennedy on May 23, 1963. In Italy there are several works by the artist, among which are the bronze giants that adorn the top of the building of the Legion of the Carabinieri in Cagliari and the bust of Giosuè Carducci in the poet's birthplace Castagneto. At his death the artist donated almost all his works to the civic museum of the village dedicated to him.
Worthy of note is also the story of Egidio Manca, cousin of Albino and priest in Tertenia who in the 50s of the last century. Don Egidio Manca designed and followed the construction of the new parish church in the town, taking care of every detail of the work, from the creation of the frescoes to the sculptures kept in it. Inside the Municipal House, a permanent art gallery is also set up and can be visited, boasting over 40 paintings by artists operating in Sardinia in the last century, including Foiso Fois, Mario Delitala, Antonio Corriga and Luigi Pillittu.