Recent discoveries of Archeology go back in Tarquinia to a very ancient time. In the past, scholars believed that the city dated back to the seventh century BC, but, apparently, it should go further back in time, even to the ninth-tenth century BC, as some type of “Villanovian” tombs  have been identified.  Scholars agree in recognizing Tarquinia in the ancient Etruscan city of “Tarchna" or "Tarchuna", the etymology of which refers to the noble “Tarquinius”. There is general agreement on this etymology, though some scholars (See G. de Santis, “Scritti minori”, Ediz. di storia e Letteratura, 1970: 342) has raised some concern, because, in his opinion, "Tarchna" should be traslated into Latin as “Tarqui-t-ius”, and not “Tarqui-n –ius”; however, the relation "Tarchna"-"Tarqui-n-ius" is generally accepted. Tarquinia is located about 200 meters above sea level in Maremma ( Latium), near Viterbo.

The city was inhabited by the Etruscans, and it is remembered in history as one of the  most important Etruscan settlements, and once it was situated on a hill called “La Civita”, which corresponds to the present “Colle Monterozzi” [“Monterozzi Hill”] . Until the early sixth century BC the city was a center of secondary importance. Since then, thanks to the intensification of business contacts with Greece, it grew in importance so as to become, in the fourth century BC, one of the major cities of the Etruscan League. Between the end of the fourth century and the beginning of the third century BC, Tarquinia, at the height of his power, clashed repeatedly with Rome, losing out from these wars (281 BC).

After the fall of Roman Empire, the barbarian invasions forced the inhabitants to move on the hill opposite, where now stands the city, which, since the Middle Ages to 1922, was called "Corneto" [“Cornetum”]. The etymology of the medieval name was probably suggested by the “cornel-tree”, a tree of hard wood, of which the area is very rich. The medieval town is mentioned in 649 in a document signed by Severinus Boethius (480 ca.-524 ca.), and its existence is corroborated by some evidences of the 743 and 861 referred, respectively, to Bishops Lando and Paul. Tarquinia rose to prominence in the ninth and tenth centuries AD, when it was surrounded by fortified walls, of which there are still important remains.

In the second half of the eleventh century, Tarquinia belonged to the Countess Matilda of  “Canossa” (1046-1115); later it became a municipality and, as an independent municipality, it strenuously set itself against the siege of Frederick II (1194-1250), in 1245. Even the internal political life of the city was not quiet; in fact, there were several popular revolts, one against the Podesta Pietro Falcone, and another in 1330, when the people rose up against the Lord Matteo Vitelleschi. In 1345 the Pope Eugene IV (1383-1447) granted Corneto the title of City. In the fourteenth century, the city was fought and it subdued by Cardinal Albornoz (1310-1367) in 1367. In 1393 the city was besieged by the Britons, who were rejected but not without severe losses; in 1413 the inhabitants offered obedience to Ladislaus, King of Sicily and Hungary (1376-1414), but, four years after, the city returned to Pope Martin V (1368 ca.-1431). In 1418, the Roman senate, in homage to Cardinal Giovanni Vitelleschi  (?-1440),  native of Corneto, granted Roman citizenship to the population. Corneto, in 1487, underwent a major wave of plague, for which it was almost completely depopulated.

In the sixteenth century, it came under the dominion of Church State, until the eighteenth century, when it was occupied by French troops. After the Congress of Vienna, Corneto became part of the Church State, until 1870, when there was the conquest of Rome, and then it entered the Kingdom of Italy.