| Roma | Frosinone | Latina | Rieti | Viterbo |

The name of the region also survives in the tribal designation of the ancient population of Latins, from whom the Romans originated. In Roman mythology, the shadowy king Latinus allegedly gave his name to the region. Modern linguists postulate origins in a Proto-Indo-European language (PIE) root *stela- (to spread, extend), expressing the idea of flat land (in contrast to the local Sabine high country). But the name may originate from an earlier, non Indo-European one. Latium, originally inhabited by the Latins, extended its boundaries to the territories of the Sanniti, the Marsi and Campania thanks to the Roman conquests, taking in the lands of the Ernici, the Equi, the Aurunci and Volsci.
This territory was called Latium Novi to differentiate it from Latium veteres, which indicated the original boundaries. During the Augustus' administrative system, Latium - together with the present region of Campania- was the first Italian region. After the Gothic war (535-553) and the Byzantine conquest, this region regained its freedom, because the Roman Duchy became property of the Eastern Emperor. However the long wars against the Longobards impaired the region which was seized by the Roman Bishop who already had several properties in those territories.
The strengthening of the religious and ecclesiastical aristocracy led to continuous power struggles between lords and the Roman bishop until the middle of the XVI century. Innocent III tried to strengthen his own territorial power, trying to assert his authority on the provincial administrations of Tuscia, Campagna and Marittima through the Church's representatives, in order to tear down the Colonna's power. Other popes tried to do the same.
During the Avignon period) the feudal lords' power increased thanks to the absence of the Pope from Rome. Small communes and Rome above all, opposed the lords power raise and with Cola di Rienzo tried to put themselves up as antagonists of the ecclesiastic power. But between 1353 and 1367 the restoration of the pontifical authority brought to a total retrieval of Latium and the rest of the Pontifical States.
From the middle of the XVI century the pontifical power's definitive victory unified Latium's history with that of the Pontifical States becaming the provincial administrations of St. Peter's estate, with a governor in Viterbo and of Marittima and Campagna and one in Frosinone.
After the short Roman Republic and the region's annexation to France, by Napoleon I, Latium became again part of the Pontifical States. In 1870 when the French troops abandoned Rome, General Cadorna entered the pontifical territory, occupying Rome on the 20th of September and Latium was definitely enclosed to the Kingdom of Italy.